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View Full Version : grooving, parting or on last leg? (pics)



Tony
09-30-2013, 10:42 AM
got this in a box of stuff when i bought my lathe. don't quite recall why it never made
it into rotation (I must've tried it and not liked how it was working?) -- but I've stumbled
across it again and would like to figure it out.

I have 8-10 brand new inserts for it of different cutting widths.
The tool holder is marked Seco r150.15-2020-4 but I can't find much on that online.

Here are some pictures.

http://img.photobucket.com/albums/0903/knucklehead/DSCN3106_zps68c4f364.jpg

http://img.photobucket.com/albums/0903/knucklehead/DSCN3107_zps87022333.jpg

http://img.photobucket.com/albums/0903/knucklehead/DSCN3104_zpseeca65f3.jpg

The holder has obviously seen some better days. When i tighten down the insert its driven
slightly askew but I can manage it to get it straight and then tighten harder.

I tried one of the larger 0.120" (3mm) .. about 1000 rpm on 1" round. got 1/4" in and the
tip of the tool (the large square section) just snapped from its tang (or whatever its called).

I was going pretty aggressive but getting great chips. much better than my HSS parting blades.

By the looks of it the biggest I could part off is maybe 2" round.

is this support trashed? if you can tell from the photos.

Thanks
Tony

LKeithR
09-30-2013, 12:28 PM
...is this support trashed? if you can tell from the photos.

Looks like it to me. That type of tool can work really well but as soon as you damage the seat all bets are off. Try a couple more cuts at reduced speed--drop down to 500 RPM or less--and see what happens. I'm guessing that you'll have another "incident". You might find that the tool will work OK in aluminum or brass but I wouldn't trust it for anything important...

Jaakko Fagerlund
09-30-2013, 01:02 PM
The support is missing, probably broken previously in a catastrophic mishap. The insert should be supported from all of its bottom side, so because the inserts V-shape is seen, the support is not as it is supposed to be.

Other than that, the tool looks to be a grooving tool. You can purchase various shape inserts, at work we have something similar for making O-ring grooves etc., and one other holder that has a curved support to allow plunging in to the end of a work piece.

Tony
09-30-2013, 01:06 PM
thats what I was afraid of, thanks.

Maybe I'll just braze the inserts I have onto some HSS parting blades and use them that way.

any recommendations for good quality parting tool with reasonably priced inserts? I'm a big fan of thin.

DR
09-30-2013, 01:47 PM
thats what I was afraid of, thanks.

.................................................. .................................................. .....................

any recommendations for good quality parting tool with reasonably priced inserts? I'm a big fan of thin.

That's a tough one, reasonably priced and good.....

Iscar pioneered these type inserts (I mean ones that look like yours), initially they were self locking in a spring pocket with no clamp screw. Those have pretty much disappeared from the main line suppliers, importers still have them. Stay away from them. I have a drawer full of damaged holders.

There are some new lines of parting tools with double ended inserts and nice clamping for a rigid grip on the insert. I can't think of names now, they won't be cheap though.

Still, the problem with any of these insert parting tools is if the insert should break or come loose the holder is most times damaged as your is, unless you have a very fast response.


As nice as carbide is for parting, rolls up a nice chip when working correctly, a "P" type HSS blade is hard to beat. I use the
P3N, 3/32" wide for most work in the CNC when they run unattended. They also come with a brazed carbide top for tougher material. They're pretty much bullet proof and they do roll up a nice chip. You need a holder for the blade. You should have a good flood coolant.

Boucher
09-30-2013, 11:36 PM
The kennametal tool in the lower left is my best for most jobs.
http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0168.jpg (http://s109.photobucket.com/user/boucherbyron/media/IMG_0168.jpg.html)
The inserts are $17 but last a long time.

Tony
10-01-2013, 08:27 AM
http://img.photobucket.com/albums/0903/knucklehead/tooling/DSCN3111_zps8fc6e496.jpg

http://img.photobucket.com/albums/0903/knucklehead/tooling/DSCN3112_zps0fb681f4.jpg

not the greatest brazing job.. other side looks way better i swear. :)

http://img.photobucket.com/albums/0903/knucklehead/tooling/DSCN3117_zpsfb75b0b8.jpg

Tony
10-01-2013, 08:28 AM
http://img.photobucket.com/albums/0903/knucklehead/tooling/DSCN3123_zps0ec7c03f.jpg

http://img.photobucket.com/albums/0903/knucklehead/tooling/DSCN3125_zps6b784f9b.jpg

http://img.photobucket.com/albums/0903/knucklehead/tooling/DSCN3126_zps4f39938b.jpg

works for me.

Tony

Euph0ny
10-01-2013, 11:45 AM
works for me.

Groovy!

(Sorry, couldn't resist...)

Arthur.Marks
10-01-2013, 12:29 PM
Hey--that works! :D As for other carbide holder types, I have to agree with DR. A standard HSS blade or the similar ones with carbide brazed on the ends (much as you've done) have won the parting job for me. The carbide inserts are excellent in a CNC with steady, reliable control in every respect. On a manual... It's just a money pit of chipped inserts and damaged holders. That's been my experience, anyway.

Jaakko Fagerlund
10-01-2013, 01:55 PM
What I've learned from using carbide insert parting tools on a manual lathe is to never feed it by hand, as hand feeding is unpredictable and usually too slow with jerky motions. Correct RPM, flood coolant and aggressive enough feed on and the bits work like charm :)

Feel no pity with carbide or it will break.

Tony
10-01-2013, 02:52 PM
carbide can smell the fear in me? haha

i've been watching some Keith Fenner on the tube. I've noticed he likes to lube his cuts with oil.. including
carbide when turning. I'll have to give that a try. I always head flood or nothing.

PStechPaul
01-18-2014, 12:28 AM
I'm having a bit of trouble with a carbide tip parting tool I got from Harbor Freight, and I might as well add to this thread as it already shows some successful cuts and tools. I was trying to cut off a 1/4" length of 3/4" 1141 steel that I had already turned down to 0.688" and added a 0.525" x 0.03" notch on the end. I had it on the live center but that probably was not necessary. When I tried to run the parting tool into the steel, it almost immediately began to squeal and chatter, and I could see where the cut was uneven. I used the same tool previously on Delrin and it was fine, but that's not saying much! The cutting tip is about 1/8" wide.

http://www.harborfreight.com/5-piece-lathe-tool-set-90741.html

http://www.harborfreight.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/i/m/image_15288.jpg

[edit] The reviews for these cutting bits were mostly bad, and said that there was not enough relief for the cutting edge. I didn't look at it too carefully but that's what it seems like. I might have some diamond rotary tool wheels that might work to see if things improve. Otherwise, I have a blade type parting tool that is just HSS and maybe that will do the trick.

I found the following video about using a parting tool and what he has is much thinner. I'm not sure if my problem is the tool or my technique or the lathe itself. It was too cold in my workshop to do much more and my back is hurting so I'll have to try again tomorrow. TIA.


http://www.youtube.com/watch?v=rkWktsK-fwM

boslab
01-18-2014, 12:39 AM
Why dont you just rebuild the tip seat with weld and grind to shape, at least that will rescue it and allow you to use different shaped tips too?
Just a thought
Mark

J Tiers
01-18-2014, 12:53 AM
I have one of the similar spring-seat insert parting tools. No extra inserts, and I don't know what kind it takes.

However, I use it for hand-fed parting, running "way too slow for carbide" and it does very well. Only problem is it is a bit wider than what would be best, so it takes a larger kerf than I'd like.

Even so, it is 100X better than any POS blade type HSS parting tool. Those things should be thrown in the scrap bin as near as I can see. I'd rather use a parting tool ground from a regular cutter blank than a limber and snaky blade-type parting tool.

The key to the insert tool is in two features.

1) the end of the insert is slightly wider than any other portion of it.

2) The form of the cutting end of the insert is such as to fold the chip in on itself slightly.

Those features seem to be what makes it work so well. I wish I had another one for larger diameters, (and some more inserts). Maybe I run it "too slow", but I don't care, it works.

PixMan
01-18-2014, 01:16 AM
I have both HSS and carbide insert parting tools. The HSS one hasn't been on the machine in years because I know how to use the other, better ones in the right way.

The key to success with carbide insert parting tools is FEED the thing. I generally run 0.002" to 0.003" per rev with my 1.5mm (0.059") one, a little higher for my 3mm (0.118") one and plow at 0.006" to 0.009" with those over 6mm.

Rigidity in the holder is paramount to good clean cutoffs. I mostly use my integral blade holder blocks for parting, and save the monoblock holders (like the one shown in the OP) for grooving and groove-turn operations. As J Tiers says, the top form geometry of the carbide inserts will thin the chip and curl it up like a watch spring so it ejects from the cut.

Here's some (not all) of my tools:
http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/photobucket-7668-1315256060736.jpg

And here's a couple shots of the top form geometry (a.k.a. chipbreaker) on the 0.059" and 0.157" ones:
http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_1406-r.jpg
http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_1430-r.jpg

As for the original question, that holder is toast. An unstable insert is worse than a good HSS blade. If you can find a good holder for the remaining inserts on eBay, go for it.

P.S. - Those tools posted by Paul are the worst excuse for brazed carbide tooling ever created. Get a torch and remove the carbide for the scrap bin, use the crappy steel as key stock or spacers.

PStechPaul
01-18-2014, 01:26 AM
Here is an image of the piece I was trying to part. You can see the shallow groove and the chatter marks. The other machining doesn't look very good either, but again it was a HF tool, and I think a bit of the cutting point may have broken off:

http://enginuitysystems.com/pix/Lathe_turning_parting_steel_1117_800p.png

Here are images of the evil tool bit itself. It appears that the top surface was ground, but the facing surface does not seem to have been touched and it looks like a 90 degree angle without cutting relief. Plus there was still some paint on that edge.

http://enginuitysystems.com/pix/Carbide_parting_bit_1_800p.png

http://enginuitysystems.com/pix/Carbide_parting_bit_2_800p.png

lakeside53
01-18-2014, 02:14 AM
I would toss those far away from your lathe... $17 for a set? Way too much for what they are. Sorry, but they are junk; maybe you can use them for knocking concrete off old barbells before getting out decent tooling.

I have an almost identical set that Pixman shows above, and many quality inherited HSS that gets use now and then. If there is any piece of lathe tooling that need to be quality, it's that for parting. I use the carbide insert type on a manual lathe - no issues - they are probably the toughest inserts I own. I feed aggressively, usually under power feed. Dial on the tool for exact 90 degree to the work, and copious lube.

darryl
01-18-2014, 03:55 AM
I have no knowledge of any of these cutters directly, but I will say that in my experience, there is a night and day difference in performance between the el cheapo and the good ones. When you buy the cheap ones, you are just throwing away money and buying into frustration. It isn't worth it.

Jaakko Fagerlund
01-18-2014, 05:35 AM
Now that tool Paul showed looks like blunt force trauma, no wonder if it tries to vibrate like crazy. You could try rescuing it with just a little grinding, but I'm sure it would be just for sh1t & giggles as those sets tend to be crap.

Black Forest
01-18-2014, 12:47 PM
I use a carbide insert parting blade like the one in Pixman's photo. The one on the right with the single edge insert. This is on a manual lathe. It likes 800 rpm and .97mm/rev. I drip oil in the grove while it is parting. I also hand feed it but I found I got too aggressive with the feed because I know it likes to be fed aggressively. I use it on everything and it parts great. Mine is 3.1mm wide. I bought a box of inserts maybe three years ago and I still have half of them left. I part a lot also. It is not like I part once a month. Mine is a Walter brand holder and inserts.

J Tiers
01-18-2014, 03:43 PM
That red parting tool has several problems.

1) it does not appear to be at all sharp... I see what appears to be a substantial radius on the "edge"

2) The top surface is rough.... that will make the swarf catch and pile up.

3) sides appear to be parallel, so it will tend to try to shave the sides of the groove, and will rub because it is parallel and not relieved below the edges

4) The holder may or may not be narrower than the carbide, if not, it will jam in the groove.

You could grind it to work.... you already own it.

I have several HSS ground grooving/parting tools, ground out of regular HSS blanks. They work , but not as well as a proper insert parting tool.

Key to any parting task is getting the tool absolutely parallel to the crosslide travel. If you fail in this, you will have the tool rubbing or trying to cut on the whole depth of the cut groove. It will jam, squeal, chatter, tend to get off-line, and won't make a good clean cutoff.

Lay it against the front of the chuck body, then tighten down the toolpost, which will get it in line if done carefully.

DR
01-18-2014, 03:59 PM
.................................................. ..............................

Even so, it is 100X better than any POS blade type HSS parting tool. Those things should be thrown in the scrap bin as near as I can see. I'd rather use a parting tool ground from a regular cutter blank than a limber and snaky blade-type parting tool.
.................................................. .................................................. ....................

The key word here is "POS".

As I mentioned previously the PN-3 T-type HSS parting blade is somewhat of an industry standard. 3/32" wide, using a special holder designed only for it, good for up to 1" material, and a bit larger. Nothing limber or snaky about it sticking out a little more than 1/2" from the holder.

Hardinge made several classic automatic lathes pre-CNC, those came from the factory with holders for the 3/32" parting blades.

PStechPaul
01-18-2014, 07:20 PM
I just finished touching up this parting tool. I used a diamond rotary bur to grind a reasonable relief on the cutting edge, and a slight curved portion of the top, then I finished it up using diamond files. The cutting edges actually feel sharp now. It's like having real knives and scissors instead of the "child-proof" safety items we got to use in nursery school. Here are some images of what I've done. It's not perfect (and never will be) but I think it will work a lot better now. I'll give it a try in a little bit, but here are the pictures:

http://enginuitysystems.com/pix/Carbide_parting_bit_5_800p.png

http://enginuitysystems.com/pix/Carbide_parting_bit_6_800p.png

http://enginuitysystems.com/pix/Carbide_parting_bit_4_800p.png

http://enginuitysystems.com/pix/Carbide_parting_bit_8_800p.png

wierdscience
01-18-2014, 07:55 PM
I've pretty much tried them all and the best I have found are the Manchester type.Both the anvil and the clamp are replaceable for about $25 so a crash isn't a total loss.
http://img.photobucket.com/albums/0903/wierdscience/0243285-11.jpg (http://smg.photobucket.com/user/wierdscience/media/0243285-11.jpg.html)

PStechPaul
01-18-2014, 09:09 PM
OK, the reground parting tool worked a good bit better, but it still chattered and whined as I got deeper into the groove. It seemed a little better if I fed the tool more aggressively, but it still didn't feel "right" so I stopped. I had a set of mini-lathe tools from Harbor Freight that cost about $50 total, and it had a parting tool with a thin 1.4mm x 5mm M2 blade.
http://www.harborfreight.com/30-piece-mini-lathe-tool-kit-3448.html

Here is the tool:

http://enginuitysystems.com/pix/M2_Parting_Tool_1_800p.png

http://enginuitysystems.com/pix/M2_Parting_Tool_2_800p.png

It started cutting OK, then it began chattering and squealing a bit. It also seemed to "walk" along the horizontal axis, so I will probably need to lock down the carriage. After a little more cutting, I found that it settled down and produced nice chips with very little noise, if I fed more aggressively. I have manual feed, so I just cranked for a bit and then backed off. I got down to where I was almost done, and then stopped to look at it more carefully. I think it looks pretty good, and so now I just need to finish parting the piece, drill a through hole, face the ends, and clean it up. It's basically a shaft collar with an offset to hold the rotor of my SRM prototype.

http://enginuitysystems.com/pix/Lathe_turning_parting_steel_1141_2_800p.png

http://enginuitysystems.com/pix/Lathe_turning_parting_steel_1141_4_800p.png

RichR
01-18-2014, 09:16 PM
Hi Paul
I think locking down the carriage while parting off is the right thing to do.

J Tiers
01-18-2014, 09:21 PM
Hi Paul
I think locking down the carriage while parting of is the right thing to do.

You are Flipping-A right it is!

PStechPaul
01-18-2014, 09:56 PM
Actually, I have never done that and I didn't know how. But I see now that it only requires stopping the leadscrew by disengaging the gears, and then flipping the gear engage lever. There is also a gear lock lever. I don't know if that is needed as well.

J Tiers
01-18-2014, 10:16 PM
There is commonly a screw on top of the carriage near front way that locks the carriage. Dunno about your machine, it might not have one.

In the video, you should need only a drip of heavy cutting oil every few seconds. A spray is inefficient, gives too much, and isn't cost-effective. But it worked for you.

However, I'd have the parting off point a lot closer to the chuck. That cuts down on screaming and gnashing of teeth, by both you and the machine.

Wheels17
01-18-2014, 10:20 PM
I concur with locking down the carriage. Not only does it reduce chatter, it will prevent another problem. I have a nice inserted cutoff tool that I got when I bought my lathe. One day when I was in a hurry, I grabbed the carriage feed instead of the cross slide crank and gave it a twist. Ruined the part and the insert, and popped a chip out of the tool. The tool lists for about $50, which isn't really in my budget, but then again, I'm sitting on about $65 worth of inserts. I'll make a decision someday.

Boucher
01-18-2014, 10:35 PM
Proper sharpening on a fine diamond wheel at 7 on each side and front end will make the Red Brazed carbide tool cut surprising well. I had a couple of those and was pleasantly surprised. I hate to be a bearer of bad news but your sharpening of that tool leaves a lot to be desired.

PStechPaul
01-18-2014, 11:05 PM
J Tiers, the video was not me. It was just something I found to learn how to use a parting tool. The part does look a lot like mine, and the lathe is similar, but mine does not have the power feed. I used a small amount of cutting oil, and I had the piece chucked closer to the headstock.

I know the sharpening job was not all that good, but certainly better than how it was. I used a cheap HF hand held rotary tool and the bur was not well balanced, so it vibrated and made it hard to take clean cuts. I probably need a proper tool grinder to do it right. But the carbide bit was not well centered in the holder, so I would need to grind part of that as well. I'm just happy to have seen some improvement, and know that I might be able to touch up a carbide tool with diamond burs and files.

[edit] I found a good source of basic information on parting, as well as other operations:
http://www.mini-lathe.com/Mini_lathe/Operation/Parting/parting.htm

RichR
01-18-2014, 11:45 PM
Hi Paul
When I ground my parting tool, I tapered the sides so the top is wider than the bottom and looking from the top the tip is wider and
gets narrower approaching the tool holder. This minimizes any dragging by the side of the tool.

PixMan
01-19-2014, 01:32 AM
Paul,

Not trying to be mean but for the $17 spent on the brazed tools that have carbide made from dirt in the Chinese parking lot (where the donkeys dump) and the $50 spent on ANY Harbor Freight cutting tools, you could have had a decent carbide insert tool that works.

http://www.latheinserts.com/1-2-INDEXABLE-PART-OFF-TOOL-404GTN20016.htm?categoryId=-1

This forum has a wealth of information and this is one subject which has come up time and time again. I urge anyone who is considering buying tools to use this resource to get good information before spending money. Quality tools only cost once. Crappy ones mean spending money over and over again.

J Tiers
01-19-2014, 10:51 AM
Hold on there..........

it is *NOT* necessary to have the "best parting insert tool" to do the job.

The red parting tool WILL WORK FINE if modified as several have suggested.

AFTER MODIFICATION... get it aligned straight with respect to crossfeed, chuck the part so the cutoff is close to the chuck, and drip a bit of oil on it when it seems to be running dry....Then you can get a lot of parting done.

Even the HSS parting tools can work, if you don't stick them out any farther than you actually need, and don't stick out more than maybe 15 or 20 x the width (a total guess) at the most. Their problems are that they are rather flexible, they are not tapered in width so they tend to drag on the sides, and mostly they do not fold the chip as they cut.

But even with their issues, they have been used for years, and if you align correctly etc, they will work.

The insert tools work *BETTER*, but the others *can and will* work.

Think of them as a "one tooth saw" and then the considerations you need to concern yourself with will be clearer, maybe...

A saw needs some "set" to the teeth so it doesn't drag badly.

A saw needs to have well-formed teeth. They need sharp edges on the end of the teeth, and relief so the points can dig in, and are not hung up on the area just below the edge.

A saw needs to be able to clear out the chips, so the "gullet" of the tooth needs room for the chips to flow out, and a decent form to help them get out without piling up.

The difference is that the parting tool is never outside the cut, and saw teeth are. So the deal about clearing chips is much more important.

lakeside53
01-19-2014, 11:34 AM
... but considering the source, no matter how you "sharpen" or modify the tool, the quality of the carbide will always be in question. Even if one set appears to work, will it be so the next time you buy? Carbide tipped is for hard or difficult materials, or longevity. I wouldn't use the HF carbide tooling for those purposes.

Black Forest
01-19-2014, 11:40 AM
Mr. JTeirs how can you say those red brazed carbide parting tools will work fine if ground and setup correctly? The carbide in those cheap imported tools could be so bad that a HSS blade will usually part better and certainly last longer. The carbide is so inferior in some of them, maybe not all, but how can you tell which batch is good until you have dumped more money than what a good quality insert parting blade will cost you. It is a crap shoot at best. Maybe the first time you get lucky and get a cutter that will actually work but the next one you buy won't necessarily be the same grade and quality carbide.

That is why I use inserts exclusively in my shop for all my metal working needs except for special ground contour tools. I try as much as possible to eliminate the need for them in my designs. I hate to waste money, time and lose the rest of my hair with inconsistency. When I go at a piece of steel with my Walter tooling I know what it is capable of so if things don't go right I know I need to change either feed, speeds, or both not the tooling. It just takes the quess work out of getting things dialed in correctly.

I am a novice at all this but because I chose early on to use good quality tooling I have progressed to making usable workpieces very fast by eliminating as many of the variables as possible. When I have problems in my shop I can go look in the mirror and find the problem. Not my tools. Yes I know great things have been made with not so great tools but it goes faster and quicker with good machines, good tooling AND a good hand using the tools.

J Tiers
01-19-2014, 12:15 PM
Mr. JTeirs how can you say those red brazed carbide parting tools will work fine if ground and setup correctly? The carbide in those cheap imported tools could be so bad that a HSS blade will usually part better and certainly last longer. The carbide is so inferior in some of them, maybe not all, but how can you tell which batch is good until you have dumped more money than what a good quality insert parting blade will cost you. It is a crap shoot at best.

I never said they would work perfectly..... I said it would work fine.. "acceptably"

Good tools work better than worse tools, of course.

I have used a lathe that you would never have considered owning, and made good parts with it. I have used less than great tools to make good parts. I have used nasty parting tools to part off parts. It worked well enough.

NO parting tool will give as good a surface as a facing operation unless everything is perfect, grind, type, feed, even the material type vs the grind and type of tool. So aiming for perfection before starting "general parting tasks" is just not required.

He already owns the tool. He has used it and it did not fall apart, so it should continue to stay together. he even parted something with it, as I understand the posts.

It will part off parts, even if the carbide is less than great, or is the "wrong type". "Wrong" carbide is not very wrong when you are not using it to the maximum, and he is unlikely to do that with his machine, which is not a big Springfield or Monarch (IIRC). ANY carbide is harder than HSS, it will cut steel is reasonably sharp and ground right.

After using it for a while, I guarantee the owner of that "fine tool" (urp) will know quite a bit about parting off that can be learned in no other way. And the parts will get parted off.

So, remind me again why he MUST buy an expensive parting tool before attempting any more parting-off tasks?

Black Forest
01-19-2014, 12:29 PM
I never said they would work perfectly..... I said it would work fine.. "acceptably"

Good tools work better than worse tools, of course.

I have used a lathe that you would never have considered owning, and made good parts with it. I have used less than great tools to make good parts. I have used nasty parting tools to part off parts. It worked well enough.

NO parting tool will give as good a surface as a facing operation unless everything is perfect, grind, type, feed, even the material type vs the grind and type of tool. So aiming for perfection before starting "general parting tasks" is just not required.

He already owns the tool. He has used it and it did not fall apart, so it should continue to stay together. he even parted something with it, as I understand the posts.

It will part off parts, even if the carbide is less than great, or is the "wrong type". "Wrong" carbide is not very wrong when you are not using it to the maximum, and he is unlikely to do that with his machine, which is not a big Springfield or Monarch (IIRC). ANY carbide is harder than HSS, it will cut steel is reasonably sharp and ground right.

After using it for a while, I guarantee the owner of that "fine tool" (urp) will know quite a bit about parting off that can be learned in no other way. And the parts will get parted off.

So, remind me again why he MUST buy an expensive parting tool before attempting any more parting-off tasks?

Working fine and working acceptably are two different things. And acceptably to whom? Also I didn't say he MUST buy a quality parting tool. I think I wrote he SHOULD if he values his time.

First off Tony is no dummy. He knows his way around a shop. He thinks logically most of the time (he married an Italian woman I think so this might come into question!) He likes to build things and does a good job. He seems to have good tools and if not when he buys it/them he fixes them.

Why dick around with questionable tooling? It makes no sense unless one just doesn't have a choice. I think he has a choice.

In all honesty what type of tooling do you prefer? I bet it is insert tooling.

mattthemuppet
01-19-2014, 12:39 PM
well, at the very least, I'm sure Tony and Paul have learned a lot about parting tool geometry and use that will stand them in good stead in the future :) We use the tools we have and when we have more money/ experience, we buy better (or more) tools. It's all a learning experience at the end of the day.

PStechPaul
01-19-2014, 01:25 PM
Yes, I have learned a lot from this discussion and from my experience on this part with the tools I have. I am an "occasional" machinist and I just want to be able to make some things and learn as I do. The HSS blade works fine for my needs, and I really prefer it to the carbide tool, which is really too wide. The thin HSS blade seems to be ground properly with a slight angle on each side and a larger angle (7 degrees?) on the cutting edge. Maybe the carbide tool needs such a large angle as well.

I agree that, in general, it is best to buy good tools from a respected brand, but I would be looking at thousands of dollars of tooling to get an assortment that included everything I may need. I don't want to buy another tool every time I find the need for one thatI don't have, so I got the set of five carbide bits (which IIRC I got on sale for less than $10).

And also, I tend to enjoy a challenge which sometimes involves getting something for cheap or free and then figuring out how to fix it or make it work better. I even tend to gravitate toward people who have problems, but I've found I can fix mechanical or electronic items much more readily. I'm happy with what I have, but if I find I am using a tool a lot and it seems to be giving problems I can't fix, then I'll certainly buy a good one.

Thanks for the very helpful discussion. :)

J. Randall
01-19-2014, 02:57 PM
Working fine and working acceptably are two different things. And acceptably to whom? Also I didn't say he MUST buy a quality parting tool. I think I wrote he SHOULD if he values his time.

First off Tony is no dummy. He knows his way around a shop. He thinks logically most of the time (he married an Italian woman I think so this might come into question!) He likes to build things and does a good job. He seems to have good tools and if not when he buys it/them he fixes them.

Why dick around with questionable tooling? It makes no sense unless one just doesn't have a choice. I think he has a choice.

In all honesty what type of tooling do you prefer? I bet it is insert tooling.

BF, this thread was started by Tony, but the last part has been about a problem Paul was having with his cheap tooling.
James

J Tiers
01-19-2014, 04:02 PM
In all honesty what type of tooling do you prefer? I bet it is insert tooling.

Naturlich.....

But I have had to use what I had many times. it worked, and I am glad I did that, actually.

I think we answered Tony's question.... and he already has the tooling, but it has problems. Paul may also have insert tooling, I'm not actually clear on who has what.

As for what is acceptable tooling..... I have used all of these, recently. They all work acceptably, when used correctly. The insert tooling is not perfect either, but it can be nicer to work with. I use these or whatever I think would work better for what I am doing. I don't HAVE TO use the insert tool, although I'd like to get a couple bigger ones like it.

http://img.photobucket.com/albums/0803/jstanley/tooling/cutofftools_zpsb5e47481.jpg (http://smg.photobucket.com/user/jstanley/media/tooling/cutofftools_zpsb5e47481.jpg.html)

PStechPaul
01-21-2014, 12:28 AM
I did a bit more on this project, really just to make a couple of shaft collars, and I used the same HF blade type parting tool that had been successful previously as shown above. This time, it was going well enough, although it chattered sometimes and also sometimes seemed to grab a chunk. It seemed better when I cut aggressively, but about halfway down there was a "snap", with this result:

http://enginuitysystems.com/pix/Parting_Tool_20140120_04_800p.jpg

http://enginuitysystems.com/pix/Parting_Tool_20140120_01_800p.jpg

It seems that the blade worked its way back and it's possible that the tool holder actually struck the workpiece. That may have been what had seemed to be the grabbing which I then had to follow up with considerably more feed. But I think the tool holder was not made from very good steel and there was not very much "meat" to it where the screw is. I think I may make a new holder, perhaps from an old lathe bit (I have a bunch of them). My tool post is really made for 1/2" tool bits so I have had to use shims for the 3/8" tool bits I have and the 5/16" carbide bits as well as the mini-lathe tool set I bought.

So I still had to complete the parting operation, and I can't find another parting tool that I bought sometime ago, so I figured I would try once again with the carbide parting tool I had reground. It looked like it was riding a little low of center so I added a 14 mil shim and went at it. There was some chattering at first, perhaps because I was following the narrow groove from the other parting tool. But as I got past about 1/3 in, it seemed to settle down, and eventually I got the job done, with a fairly good finish:

http://enginuitysystems.com/pix/Parting_20140120_01_800p.jpg

Here are the parts I made. They need a bit more work, and they are far from perfect, but they should be "good enough" for what I need. I think I learned a lot from this experience, and I'm gaining a bit of confidence so that it's becoming less stressful and more fun.

http://enginuitysystems.com/pix/Shaft_Collar_20140120_018_800p.jpg

PStechPaul
01-21-2014, 03:35 AM
I think I'd like to make a parting tool using the same blade as the one in the broken tool. My idea is to make it from a 3" length of 1/2" square steel, mill a 60 degree dovetail groove to match the blade, and add a clamp on top, made from 3/4"x5/8"x3/16" steel. I can use two #8-32 screws to hold it down. Here is how it will look:

http://enginuitysystems.com/pix/Parting_Tool.jpg
I don't have a dovetail mill but I found one for about $10:
http://www.ebay.com/itm/1-PC-1-2-X-60-DEGREE-PREMIUM-HSS-DOVETAIL-CUTTER-MILLING-HIGH-SPEED-STEEL-/131064714192

PixMan
01-21-2014, 07:37 AM
If you go ahead and make a stronger holder for the little blade the holder will be better. And now that blade will break.

Quit while you're behind. You'd be $10 further in the hole buying a dovetail cutter (which also is probably crappy) and no better off. Save up for a good tool like the one I linked to. Not necessarily that one (though it's good), but perhaps we can help you find one in a 1.5mm width.

J Tiers
01-21-2014, 08:27 AM
Blade tools have worked for 100 years or so. No reason for them to stop working now. I don't care for them much, but that's largely because they don't have a chip folding groove. I could grind one, I suppose. Another reason is that most of mine have a "hook" ground in the end by prior owners, and need a lot ground off the end now, or only have a lantern post holder.

That said, I think I would change the holder design a bit.... the clamp is short, the blade will have a mechanical advantage. I would choose to make the clamp longer so the blade will be held down toward the tail as well as right at the front.

mattthemuppet
01-21-2014, 10:57 AM
Paul - just get some HSS blanks (or a selection (http://www.ebay.com/sch/i.html?_odkw=1%2F4in+HSS+tool+blank&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.XHSS+tool+bla nk&_nkw=HSS+tool+blank&_sacat=0)) and grind one into a cut off tool. I ground a 1/4x3/8in blank to a shape similar to the 2nd from right in JTiers' photo and it works just fine within the limitations (many) of my machine. Get the tallest and narrowest one you can fit in your holder - tall for support (less chatter, theoretically), narrow for less grinding. You could grind each end a different width, a different length or even different geometry for steel vs. aluminium.

Plus you'll have some spare blanks to grind other fun tools, like boring bars, threading tools and what ever you might need.

Here's my cut off bar in action. It's not perfect (might grind a chip roller on the top some day) but it does the job.
http://i1349.photobucket.com/albums/p752/mattthemuppet/Lathe/IMG_2558_zps633e96fe.jpg
http://i1349.photobucket.com/albums/p752/mattthemuppet/Lathe/IMG_2559_zps55c079ac.jpg

PStechPaul
01-21-2014, 03:12 PM
It would be good to have an assortment of HSS blanks. The following looks pretty good, with round, square, and a rectangular blade for parting.
http://www.ebay.com/itm/BARGAIN-8PCS-HSS-TOOL-BIT-BLANKS-BAR-LATHE-TOOL-MILLING-CUTTING-TOOLS-H73-/111250544499
However, I do not have a proper tool grinder and my 6" HF grinder may not be good enough to cut lathe bits very well. Even a cheap tool grinder is probably $200 or more. I can buy a lot of carbide tools or holders and inserts for that money.

But I already have a whole box full of 3/8" lathe bits, some of which are sharpened as cutoff tools, and I really don't do a lot of machining so I think I'm pretty well set. It would probably be better to invest in a dovetail cutter so I can make the toolholder as I have shown. The cut-off blade is actually not truly rectangular, as it is tapered on the sides from 54 mils to 46 mils, and the bottom appears to be a 60 degree angle which fits into the dovetail on the broken tool holder. The blade is fine and I have a spare, so I think I would like to have a tool holder for them. I agree that the top clamp perhaps should be longer, but then it would extend the tool holder out further for the toolpost screws to clamp. Maybe I could make the clamp as long as the toolholder but have the clamping screws only at the end, so that the toolpost screws would exert pressure on the entire length of the blade. And/or I could use FH screws so they won't interfere.

This small blade is really for the 7x10 mini-lathe and probably should be used only for small diameter work. I should use the 3x12mm blade for larger work, and I should get (or make) a good toolholder for that.

Also I think I need to make toolholders for my 5/16" and 3/8" tooling so I won't need to mess around with shims to bring the cutting edge to center. Ideally I should have the adjustable height toolpost but what I have should be OK. Maybe I can make a toolholder that provides a bit of vertical adjustment, like the lantern style.

Finally, once my carbide cutoff tool started getting into "clean" metal, it was actually cutting very nicely, even if it was not sharpened "properly". I think if I grind the end with a greater angle similar to that of the cutoff blade, it should work even better, and I can add a little more relief on the sides. It also may be that the RPMs were a little too high for the 0.687" diameter where it started, but when it got deeper, with less SFPM, it cut better. Also the lathe had better mechanical advantage and inertia at that point and would be less susceptible to chatter.

Thanks.

mattthemuppet
01-21-2014, 04:02 PM
any old bench grinder will do, as long as you take care to keep the blank cool as you're grinding it. Then finish off with a diamond hone or Arkansas stone (what I use). Hell, you could even use a Dremel if you have an awful lot of patience. I re-cut an overly wide cut-off bar into a boring bar using a cut-off wheel on a Dremel. I wouldn't call it fun, but it works a complete treat.

http://i1349.photobucket.com/albums/p752/mattthemuppet/Girls%20lights/IMG_3192_zps6be5e7af.jpg
http://i1349.photobucket.com/albums/p752/mattthemuppet/Girls%20lights/IMG_3205_zps081c6579.jpg

Jaakko Fagerlund
01-22-2014, 03:57 AM
What sort of speed are you running when parting off? And better err on the low side rather than dead nuts center with the tool.

dian
01-22-2014, 11:51 AM
because its going out of the cut, when it flexes, right?

well, i have been wondering about that. on one hand you want to have maximum rigidity, when parting off, you lock the carriage or use a special holder, eliminating the compound for that reason. on the other hand there are the "gooseneck" type holders or holders with a slitt, that provide flexibility and take the tool out of the cut, when it bites. so whats the strory?

btw, i usually go to these tools for parting off:

http://i973.photobucket.com/albums/ae218/romandian/1048_zps3508a3f4.jpg (http://s973.photobucket.com/user/romandian/media/1048_zps3508a3f4.jpg.html)

you touch them up on the diamond wheel and they live forever. the bigger one iv had for 20 years or so.

the holder for the narrow blade is glued together with flexible glue and goes into the toolpost.

if you use the brazed on tools, put coolant on them generously, as otherwise the brazing will let go.

PStechPaul
01-22-2014, 12:23 PM
The little curved section on top at the cutting edge probably would help. I have a HSS turning bit sharpened that way and it works pretty well. I guess there are many ways to get a job done, and they may be judged on speed, quality of cut, simplicity, and cost. As for buying or making tooling, it's usually good to buy the best, but then again it may be "better" to make or fix what one has, and spend money on other things, especially when I'm not making money on these jobs, and I do work like this only occasionally. It is also an educational experience to learn why some things work and others don't, or not as well.

It's too cold today to work in my unheated shop. It was only about 6F overnight and today at noon it was not quite 14. It's only about 40F downstairs and the woodstove is slowly bringing that up, but the floor is below freezing and my dog's water has a crust of ice. In my bedroom it was up to 60F last night but by 9AM the woodstove had cooled off and now it's only 54 here. Gotta get some more wood from the pile and get a bit more comfy. This "polar vortex" is expected to hang around for at least a week. Brrr!

dian
01-22-2014, 12:30 PM
get yourself a drink, youll be warm (after a couple).

PStechPaul
01-22-2014, 01:24 PM
I should hang a small keg of brandy around my dog's neck, like the St. Bernard ski rescue dogs in your country. But of course you must drink the alcohol after you have moved into a warmer place. Otherwise it promotes frost-bite and then hypothermia and then this warm fuzzy feeling just before you pass out and become a winter lawn ornament. Here's a good story appropriate for today's arctic cold:

http://www.pagebypagebooks.com/Jack_London/To_Build_a_Fire/To_Build_a_Fire_p1.html

dian
01-22-2014, 01:47 PM
fun reading. will finish tomorrow.

Jaakko Fagerlund
01-22-2014, 03:18 PM
because its going out of the cut, when it flexes, right?
That and the fact that then it actually cuts. Because if it is even half the hair up from center, it will rub and rub and rub until the downward force is enough to actually bend the tool down and it kind of "digs in" and starts cutting. Sure and fast way to destroy any cutting tool, so yep, better to err on the little bit under side :)

PStechPaul
01-22-2014, 04:42 PM
I think it depends on the diameter of the work piece and the angle of the tip of the tool. See the following, which uses the same angle as my small parting blade, and see that it can sit high by 96 mils before the tip does not engage the work piece (3/4" dia). There is a likelihood of grabbing with the tool set above centerline, whereas below centerline it will tend to flex away from the work and chatter.

http://enginuitysystems.com/pix/Parting_Angle_Position.jpg

mattthemuppet
01-22-2014, 04:54 PM
it's tricky and something that requires a lot of trial and error on small lathes due to the flex of the machine and the tool. I aim for dead on center with little tool overhang, then ever so slightly above center with the tool further out, so that flex pulls it ever so slightly below center. If I start with the tool a smidge below center, then the piece wont part off properly as there'll still be a stub left. that or the tool will be pulled underneath the stub and jam.

PStechPaul
01-22-2014, 05:21 PM
I think it depends on where the pivot point of the flex occurs. If that point is low on the blade, or at the base of the toolpost, the cutting edge will tend to rotate toward the center of the part and grab. If it flexes near the top of the blade, it will dig in only a tiny amount. Having a little bit ground off the top of the blade (as shown in post #53) will tend to provide a good cutting edge a little bit below center, and that may help.

It is tricky because the radius of the work decreases to zero at the center and also the surface speed decreases. The same happens when facing, but it is not as critical since the amount being removed is usually constant, especially the last cuts.

On the piece I was making, the first cut with the thin blade left a tiny stub that I was able to break by flexing the pieces. For the second piece, I first drilled a 0.203 hole a bit deeper than the part, and so parting occurred at a 0.1" radius.