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Spindle
01-25-2009, 11:36 AM
I just got a quick change tool post that has a holder for 11/16" blades and don't have any that size. I've been using HSS blades to cut the following materials:
1. Cored bronze for plain bearings
2. Mild Steel
3. Brass
4. Aluminum
5. Nylon
This is done on an old Rockwell 10" lathe. What type of blade(s) should I get? I've seen P type, T type, Hollow Ground, Carbide Insert, and it seems to go on for ever. Any suggestions?:confused:

DR
01-25-2009, 11:56 AM
You want to use the 11/16" quick change holder, right?

Then you have to use the type blade that fits it.

Not all blade styles fit any old style of blade holder.

Given a choice, I prefer the P style. Re-sharpening is done on the end only. IMO, you should stay away from blade styles requiring sharpening the top side.

Spindle
01-25-2009, 04:06 PM
DR-
Thanks for the help! Since I can't post a picture here, it's at wttool.com part number 1643-0090. Described as Universal Parting Blade Tool Holder #7.
Is that a P style holder?

Rex

Bill Pace
01-25-2009, 04:40 PM
Of the 3 types, none of them really seem to be actually designed for that holder. I had several of the type generally called "double beveled" and have been using them for some time. I think on any of them youll need to take a moment to try and get it as perpendicular as possible in the straight sided holder. If youre gonna order some anyhow, go ahead and get one of each, the HSS ones arent very expensive, and check out how the fit up.

I sitting here looking in a Shars catalog and a 'P' type in 11/16" x3/32" is $3.90, and in beveled 11/16x1/8" is $4.90. A carbide tipped "T" version is $7.15. http://www.shars.com/

By the way if you need any more of the QC tool holders, CDCO has the B styles for cheap, that one you got isnt much better, but the regular ones are $12 http://www.cdcotools.com/index.php

Spindle
01-26-2009, 08:24 PM
Bill-

One of each sounds like a good plan. Seems like the double bevel type would be the most stable in this type of holder, but I'll try them all. CDCO didn't have my size, but Shars does.

Rex

BadDog
01-26-2009, 08:53 PM
If I might offer a suggestion, part off blades are not a place to fish the bottom of the barrel. I speak from experience, I did try to use "Indian" and "Chinese" no-brand. Nothing good to report, quite a bit of bad, borderline worthless and FAR too hard by all appearances. They break and chip like you wouldn't believe. You can get away somewhat ok with crap bits for normal turning, but I think that crap parting blades may be at least partly to blame for all the bad press parting gets (that and trying to part steel on tiny/flimsy lathes). I've now got (and had for some time) some better ones that actually work rather well. You WILL notice a significant difference in a side-by-side double-blind taste test...

That said, I also got a Sandvik insert parting blade a while back and it leaves everything else in the dust.

Spindle
01-27-2009, 07:20 PM
Mr. Dog-

Thanks for the Sandvik reference. I'm not shopping based on price right now, I'm trying to move from the rocker post world to the quick change tool post world and don't know what to ask for. What I'm after is a stable parting solution for the materials and equipment listed in the original post in this thread. If carbide inserts and holders are the best way to get a high quality known quantity, then that's what I'll get.
I looked at carbide inserts and see that there are several variations. I think I need a book or chart or something I can base my decisions on. Anything like that available?

motorworks
01-27-2009, 08:05 PM
I second the thought on NOT using cheap.

What size tools can your QC take
i.e. 1/2 square,5/8" etc

How big to you plan to part?
Bushings, solid etc

Kennametal, Iscar and others make a square holder that will
part up to 2.5" diameter
See link below to a Kennametal page. Pics should tell all:
http://www.kennametal.com/e-catalog/ProductDisplay.jhtml?XMLArg=4098.xml&id=4098&level=&pid=1637340&navAction=push&item=category%3A4098&logo=

eddie

BadDog
01-27-2009, 08:15 PM
I have no idea where you would find a book or the like that covers this. A friend of mine had a Sandvik. I loved how well it worked. He not only had a couple of new spares (bought it from him basically at wholesale) but also has a box full of spare inserts in both L, R, and C configurations. This is the smallest/thinest of the Sandvik blades, they make a variety with different support for max hang out, width of insert/cut and so on. I liked it so much that I've since picked up several other size (much cheaper) on ebay, along with inserts in a variety of styles. Newcomer is often in the Enco sale catalog and seems to get good reviews. As mentioned, there are also versions from Kennametal, Iscar and others. There are also the Manchester "Dog Bones" and many other varieties with varying options and capabilities. I like the "blade style" I currently have, but don't have the experience to say how it fits along side the other options.

My main word of advice on that one is check ebay and other alternatives for insert cost. Shopping for price or not, those little fellows are often very expensive compared to what you typically get inserts for. And if you get an odd-ball, then getting inserts cheaply on ebay (or otherwise) may be a problem. With an odd-ball, you may even have limited options for new, which can make them even more expensive.

BadDog
01-27-2009, 08:21 PM
Oh, and I was using insert parting tools back when I was using HSS tooling almost exclusively. Just for rough numbers on a functional level for my old 11" Rockwell lathe, on a scale of 1 to 10 with 10 being "I can't believe it could be any better" and 1 being "Where's my @#% hack saw!!!". I would put the cheap parting blades at a 2 if I feel like being generous, probably more like 1.5. A good HSS parting blade for most materials is more like a 6 or 7 if kept sharp. Quite serviceable. But that Sandvik with a good/fresh insert is a 9 or 10. Rolls up 4140 like a clock spring, and I've got examples 1" in diameter rolled up nice-n-tight in a lovely blue-purple color. :D Beautiful cuts and no futzing around with clearances and such, just make sure you get it square and hit the power feed!

Spindle
01-27-2009, 08:45 PM
Motorworks-
The parting tool holder takes 11/16" blades, the other holders are good for 5/8". This set is a BXA or 200 series from Wholesale Tool. Most of my current projects are bronze flange bearings in the 1.125" max OD range, but I will be doing some mild steel, stainless and aluminum up to @ 2.00". Those may have to get sawed and faced.

BadDog
01-27-2009, 08:59 PM
Those hold only HSS blades. The typical insert parting blades set square/level rather than using the tool holder to provide rake. I have a tool block that mounts in a common holder. That block in turn holds the blade. Some day I want to make a direct mount dovetail blade holder for my Sandviks, but frankly it works very well now so I'm not terribly motivated.

motorworks
01-27-2009, 09:04 PM
Forget the parting tool blade holder (put it on ebay)
Look at the link to the kennametal page and
find A3SCR100416
This tool will fit into your "plain" 5/8" holder
It has a max cutting diameter of 2.050"
A 3mm or .125" insert and the tool body is 5/8" square.

I use kennametal only as a reference, as others including Sandvic, Iscar , etc
make the same type of tool.
http://www.kennametal.com/e-catalog/ProductDisplay.jhtml?XMLArg=4098.xml&id=4098&level=&pid=1637340&navAction=push&item=category%3A4098&logo=
I have been using this type for years when making bronze bushings etc.
I also found this type of tool excellent for machining various types of plastics.
Two tools in one for plastic, Turn and part!

eddie
PS These can be found on ebay from time to time at great prices

Bill Pace
01-27-2009, 09:28 PM
As this post has continued and you are apparently receptive to broadening your choices for doing parting --- I would like to join the others and say (stress!) that using the holder you have, and using one of the carbide cut-off kits is ... well, theres just NO comparison. I have to say I concur across the board with Bad Dogs use of the 1-10 scale.

After a moaning sessions about parting off, one of the more respected members of the forum here (Lane) was telling me about these tools, and having learned to respect his advice, I chose the one already mentioned, from ENCO, the Newcomer. With getting the kit, you'll get everything ready to use with your new QCTP including 10 of the inserts. Get one that takes the narrow inserts, it is much easier on your lathe -- in the Newcomer its .087. Heres the one I chose ---
http://www.use-enco.com/CGI/INSRIT?PMAKA=422-2914

As mentioned, its qualifies for free frt, too;) --- use code PRPT12 (that'll expire end of the month...)

Spindle
01-28-2009, 07:01 PM
Thanks for all your time and patience in helping a new guy out. What I've learned so far here, on other forums, and some local shops is:

1.Mentioning the parting operation strikes near panic in many people I consulted with.
2. There are definate strong opinions on either side of the HSS/carbide fence. Since my brother who does most of my lathe work is most comfortable with HSS, I'll have a T-type and a double bevel cobalt blade for him. Since I don't have experience with either but am looking forward to learning, I'll have either the Kennametal or Newcomer insert tools also. Maybe I'll make a convert of him.
3. Some lathes (probably my 10" Rockwell) just aren't rigid enough to be very succesful at parting, and a trip to the bandsaw then facing may be the best choice.
4. Parting remains a major PITA for even the experienced.

Thanks again for all your help, and I'll be back with more first timer questions.

Richard-TX
01-29-2009, 03:10 AM
I used to have some pretty serious problems with parting using a parting blade holder and a HSS blade. I now use a water soluble oil dripped on the cutter using a wash bottle. No more worries.

Blackadder
01-29-2009, 03:20 AM
My take on the subject

I use a carbide inserted tool for steel with cutting oil fed into the slot, i have just parted off some 1 3/4 steel stock at 200 rpm ( this is the max depth for my parting tool) , but for cast iron ,brass and cast bronze i use HSS

macona
01-29-2009, 05:56 AM
This is where I used to get my cut off blades:

http://www.tools-n-gizmos.com/store/agora.cgi

Spindle
01-29-2009, 07:56 PM
Another tool source! Can't have too many. Thanks

Evan
01-29-2009, 09:22 PM
The secret to easy parting off is to use a thin blade. That is much more important than the blade material. For small sections I grind up a parting tool from a HSS blank with a blade profile that is zero rake on top, raked back at about 30 degrees on the cutting edge and about .063" thick. It will chop off nearly anything except for hardened material. A thin blade has a lot less work to do and the loads on the blade are much less than a thicker one so it doesn't have any greater tendency to break.

For deeper cuts I take a store bought blade and thin it down by grinding the side. I have no trouble parting off 2" stainless steel shaft or 1040 half hard steel shaft.

The Fixer
01-29-2009, 09:37 PM
I use both and agree with most of these guys, keep it as thin as possible, and use a good cutting fluid/oil for best results. Also spend the time to get it set square to the workpiece. With the HSS blades the benefit is that it can be customized to the situation. You may want lotsa rake or even a neg rake depending on material etc. In my experience with HSS most people that have problems don't keep the tool sharp, you may have to resharpen part way thru parting the part. did that part make sense? lol

DICKEYBIRD
01-30-2009, 08:25 AM
In my experience with HSS most people that have problems don't keep the tool sharp, you may have to resharpen part way thru parting the part. did that part make sense?For the most part, yes.:D

Norman Atkinson
01-30-2009, 09:23 AM
We've been through all this before and before.

The classic answer is to use a rear tool post and run the lathe forwards but using a tool inverted at a 7 degree slope. Set at exact tool height, of course.

The top of tool remains straight but has a convex grind along it. The recommended grind is a vee of 140 dgrees but I found a simple curved female grind( calm down, fellas) was enough. The front of the tool had a male 140 degree vee'd edge.

With the tool dead on to the task and the lathe running fairly briskly, the swarf comes off in a narrowed ribbon thus avoiding a jam!

So far, the rest of this diatribe about parting off, is old granny stuff talk.

All my stuff mentioned dates back to perhaps 30-40 years ago and all these stepped narrowed blades and vees ground in carbide are merely a stage on from this.
The nice thing about HSS is that it is relatively cheap and can be reground and reground on a home workshop grinder- for nothing.Moreover, it all works on a lathe which is long past its first or second flush of youth.

Norman

softtail
01-30-2009, 09:58 AM
I screwed around withh all types of blades on my similar sized Boxford VSL.

By far the best cut off tool I have used is an Iscar insert tool. It's amazing. Also turns/faces like a dream. They can be had of Ebay for pretty cheap, and inserts last a long time. My smaller lathe has zero toubles with it. I'll never mess with hss for parting again.

Norman Atkinson
01-30-2009, 10:35 AM
Perhaps the experience of thousands of other Boxford and Myford owners is wrong or mis-guided.
Despite it all, castings for the George Thomas rear parting tool seems undiminished. Moreover, the design has now moved onto a larger one suitable for applications on larger lathes than the Boxfords, Myfords and cheap sh1te Chinese 9x20's etc.

Again and again, people with far vaster experience than I have have been using castings etc from HemingwayKits. I, on a succession of lathes including a 9x20 over decades have had no problems.

It does suggest that that I have been using a failed or very inferior system all these years.

Where have I and the rest of us, gone wrong? Well????

Regards

Norman

pcarpenter
01-30-2009, 11:01 AM
Perhaps the rear inverted tool works well if the gibs are well adjusted and/or the carriage is quite heavy, but it does tend to want to lift the carriage and cross slide if there is any slack to be had there.

The bigger issue that scares me with an Aloris style QC toolpost back there is that the only thing to prevent lifting the whole tool holder off and heaving it (perhaps at the operator) is the friction of the holder's clamping mechanism. In normal use, the cutting forces are working against the stop/adjusting nut on top. Even if you sheared the adjuster screw on the QC tool holder or ripped the big nut off the top, the tool holder would just drop to the top of the compound and away from the operator.

I now have one of the Newcomer kits and another (Seco) blade and inserts that is thicker so I can reach further. Having had an "un-pretty" result once when I tried adjusting the tool point on center only using the "ruler method", I can say that on-center setup is critical no matter what tool you are using. So much so, in fact, that I would have to say that a guy can get good results with either a HSS blade or carbide insert holder...but that proper adjustment and tool shape mean more than the choice of tool. I think that often the carbide insert blades are so highly touted primarily because they have some of the correct architecture defined for you. They do also do a better job of curling the chip up and out of the way because of their molded in chipbreaker design.

On thing that the insert type blades offer is built in blade clearance. The insert is inherently centered and enough wider than the blade to guarantee side clearance and this is critical (as is having the blade square to the work and on center). If you want to use HSS blades (and I do) then I highly recommend the t-shaped blades even if you have to modify your holder to get them in proper orientation. The t-shape is strong and the necessary side clearance is already there by design.

What to me is an issue with either is keeping cutting fluid down in the cut. The continuous curly chip amost immediately pulls what was applied up and away from the cut. I intend to make a needle "dripper" as someone showed here, just for this purpose. It doesn't take lots of cutting fluid, but rather just needs to be constantly supplied.

Paul

Alistair Hosie
01-30-2009, 11:26 AM
I had some large woodworking planer blades I ground them to shape then adapted a holder for them by making a new holder fitting dovetailed it etc woks greatr.Alistair

Richard Wilson
01-30-2009, 11:41 AM
I've been parting off on a succession of elderly lathes for 40 years now, and the only one I used a rear toolpost on was a pre-war Myford, which really wouldn't part off from the front, mainly due to the split headstock bearing design. I use an Eclipse holder and HSS blade, and can part off from the front on my s---y 7x12 chinese, and on my Raglan Littlejohn. I had big trouble with the chinese lathe when I was using QC holders, but once I reverted to an old fashioned 4 way toolpost, so that the parting tool was rigidly clamped down on the top of the topslide, not overhung at the front, then those problems went away. I don't think that QC (the cheap ones anyway) or rocker toolposts are rigid enough for reliable parting off, you need to have the parting tool as rigid as possible, no overhang on the topslide, really sharp and set exactly at centreheight. Very few lathes now have those old split headstock bearings, so I can't understand why parting off still gives so many people so many problems.

Regards
Richard

3t-
01-30-2009, 12:12 PM
Good information all around but I must admit that I could use some photos or diagrams to assist my understanding of the various shapes and setups. I have little to no experience with parting off as what little I do have is not happy;)

I use a 9x20 and an Atlas QC54. I would like to learn to grind the HSS as that is what I am using (learning to use) in my regular turning and threading operations.

Thanks

Norman Atkinson
01-30-2009, 12:16 PM
The 'why's and wherefores' of successful parting off were explained in the greatest detail by Thomas in his Model Engineers Workshop Manual.

Again, I recall Ken Metcalfe writing in Model Engineer years back and there being a design which held a rear mounted parting tool in a vice like grip.
Again, I recall someone explaining in Model Engineers Workshop how he had done the grinding of the kerf to which I refered earlier. Again, Myford produced a rear tool and something similar is being sold with a 'boat like' tool holder in the UK. Yer pays yer money an' yer gets a heap of ***********?

I addressed the question of a 5/8" HSS blade and so far, I am the only one to have said 'Look, Sunshine' this is what you do with a 5/8" HSS blade!'

Ok, I CAN grind up a carbide parting tool or cut a planer blade down to size and I have a Quick Change 'How's yer father' and a lot of cast iron door stops. However, my 5/8th blade by Eclipse is upside down on the back of me Myford and Paul- I use a jam jar full of a congealed mixture of deceased wasps and once purified lard oil and a child's paint brush as an applicator.

I dab it on- face Mecca and utter a meaningful prayer and--It works every time.

And if you want to take your copy of Hamlet into the workshop- well?

'Parting is such sweet sorrow'

Norm

pcarpenter
01-30-2009, 12:20 PM
I have one of the t-shaped profile blades with a sort of v-grooved top. Get one of those and you will have next to no grinding to do. The top v-groove (chipbreaker?) is already part of the blade. The side clearances are done for you by virtue of its t-shape. You only have to grind the front to sharpen it and that's a no-brainer. You walk it up to your bench grinder wheel like the wheel were a piece being parted with the top of the blade right on center of the grinding wheel (eyeball) and grind until the wheel touches from top to bottom. The curvature of the wheel will provide some relief at the front. Move it side to side while doing this to prevent grooving the wheel.

Really slick way to do things if you ask me.

Paul

patty boy
01-30-2009, 12:28 PM
Amen to the comments about using cheap cutoff tools. I fought Chinese HSS for some time, all with poor results. I recently bought a 3/4" wide blade for carbide inserts. It fits a holder that I was using with HSS.

It wades through everything and puts a grin on my face every time I use it. The blade is a AGIH-19-2 Accupro unit with MGTN-2 inserts. This small blade will only handle up to 0.093 insert thickness, but easily cuts up to 1" material. When the pocketbook permits, I'll get a larger blade and inserts to will let me make wider cuts and handle thicker material.

Yeah, good carbide tools are expensive, but they last forever, or at least longer than I will.

Norman Atkinson
01-30-2009, 12:43 PM
Of course, there are designs to use- worn out hacksaw blades.
One of the best builders of yesteryear used them almost exclusively.

If one is loathe to such flights of fancy, you can always use a Quorn T&C which will sharpen them- not the first and last tooth but you can't have everything. Prof.Chaddock did it and I doubt that there are many here who can keep up with him.

Now this 'ere 9x20, it will take a subtable. Oi' did it and I transfered all my Myford goodies onto it. It isn't rocket science drilling and tapping a few holes here and there to suit doesn't require a genius.

Geniuses post on Photo-phuket, me-too old or thick- sorry.
I keep looking East for miracles but my old eyes
just water!

N

dockrat
01-30-2009, 01:22 PM
I have one of the t-shaped profile blades with a sort of v-grooved top. Get one of those and you will have next to no grinding to do. The top v-groove (chipbreaker?) is already part of the blade. The side clearances are done for you by virtue of its t-shape. You only have to grind the front to sharpen it and that's a no-brainer. You walk it up to your bench grinder wheel like the wheel were a piece being parted with the top of the blade right on center of the grinding wheel (eyeball) and grind until the wheel touches from top to bottom. The curvature of the wheel will provide some relief at the front. Move it side to side while doing this to prevent grooving the wheel.

Really slick way to do things if you ask me.

Paul

I also use the t-shaped blades and they work well for me. I DID have to mill out the top of the toolholder so the blades would sit flat though. As for grinding I do it as Paul said but instead of using the bench grinder I made an arbor for the stone that mounts in my chuck and set the hight of the blade with the toolholder. Here is a pic. ( wrong stone but was the one mounted on the arbor at the time for picture )

http://i253.photobucket.com/albums/hh67/Dockrat1/IMGP1192Medium.jpg

Norman Atkinson
01-30-2009, 03:58 PM
With a change of computer, I had wiped this site from my Favorites.

OK, now have a look at www.haythornthwaite.com and go into this modellers workshop projects.

Suffice to say that the Thomas rear parting tool is depicted. I made one exactly like this- and a few more identical items.

Norman

quasi
01-30-2009, 06:02 PM
Norman, thank you for the link, very impressive stuff there.

Thomas Staubo
01-30-2009, 08:16 PM
Yes, thank you for the link, Norman.
I have visited a great number of model engineering websites, but that one was new to me.


One question regarding the rear parting tool described here (http://www.haythornthwaite.com/Rear%20Tool%20Post.htm) :
Can this be used on a short-cross-slide Myford (ML7)?
When comparing the pictures with my lathe, it looks like it fits ok, but might be a bit cramped.


.

softtail
01-30-2009, 08:55 PM
Perhaps the experience of thousands of other Boxford and Myford owners is wrong or mis-guided.
Despite it all, castings for the George Thomas rear parting tool seems undiminished. Moreover, the design has now moved onto a larger one suitable for applications on larger lathes than the Boxfords, Myfords and cheap sh1te Chinese 9x20's etc.

Again and again, people with far vaster experience than I have have been using castings etc from HemingwayKits. I, on a succession of lathes including a 9x20 over decades have had no problems.

It does suggest that that I have been using a failed or very inferior system all these years.

Where have I and the rest of us, gone wrong? Well????

Regards

Norman

Glad that method treats you well. Another method that doesn't require running the tool post backwards, casting kits, or sharpening of hss is to use an Iscar or similar carbide insert parting tool.

Norman Atkinson
01-31-2009, 03:07 AM
Greetings Thomas( and all)

As it comes from HemingwayKits or just using what you have in the scrap box and 'the book', it will fit onto the back of a short boring table on the ML7.
Thomas( GHT- Thomas) designed it to part off at 2" diameter maximum.

What doesn't show up in the otherwise excellent photographs is that the 'turret' top can be rotated 90 degrees so that more space can be gained when not parting off.

May I ramble on? There are two blades and by rotating them, they lock in position with a spring loaded peg and you can use which ever thickness is suitable for the job in hand.
However, GHT was a vey clever and thoughtful engineer and you CAN change the turret or remove it but you can also fit a new turret which could take a spare lathe tool which could, say, be for chamfering work.

When I got my casting etc( a long, long time ago) it had a plan for a parting tool on on side and a chamfering tool on the other.

Thomas- my E-mail address is norman@n-atkinson.wanadoo.co.uk and I have just scrapped a 'long' ML7 and the top etc is still there.
Oddly, I'm in Newcastle for the record.

Hope the rest of you find this is interesting!

Cheers

N

Norman Atkinson
01-31-2009, 06:47 AM
Parting off? Well, not really!

I thought that if I was still a bit - crook as they say in OZ, it would make sense to pass along a few more hints from 'goggling' -sorry 'Googling'

Have a go at 'GadgetBuilder.com'. Understandably, there is a lot of stuff which appears elsewhere. Nevertheless, it is better to a bit of duplication than nothing at all.

Whilst you are in Googling mood, there is an old site- out of date and perhaps, you will not be able to get all of it. However, try 'Chris Heapy'
A Japanese modeller sort of resurrected it and newcomers will really enjoy the wealth of information.

Tell me, tell us of whether you have found both sites useful.

Meantime, more eyedrops and a rest up.

Cheers
Norman

Peter N
01-31-2009, 07:37 AM
Years ago they used to have a man with a red flag walking in front of cars to warn people of the vehicle approaching and avoid accidents.
It worked very well, but then they had to go and make progress using more modern technology and found a better way to do things Dammit $*!!

Of course, some still maintain that this was the only way to do it, and the idea should not have been forgotten, others just shrug and use the new stuff which is easier, quicker, and doesn't need the additional burden of a man in front.

Bit like parting tools really. Rear parting toolposts still work well, but a modern approach like this : http://www.greenwood-tools.co.uk/shopscr23.html works even better, even on speed and rigidity-challenged small lathes like the Myford.
I've used mine on the Myford and Colchester on everything thing from small stainless and sliver steel bars to a 2" lump on EN19T, and I would never go back .

Peter

Norman Atkinson
01-31-2009, 09:43 AM
Peter,
Sadly these new fangled gadgets come at HALF the price of a 2nd Hand professional tool and cutter grinder. I bought a Clarkson for 100.
Again, I was offered an unusual Stent which was fabricated for the same- with a heap of accessories.

I was in HongKong and have connections there. Red Flags still cost money there.

The Chinese 'Luck Money' is due by the 12th- want a coin?

Sorry, but I am living and succeding in this weird economic climate.
When I went to college- one grossed up 50 as it was paid out of net and therefore taxed income( at 40%) Hasn't changed much- it was 50% then

Regards

Norman

3t-
01-31-2009, 10:14 AM
dockrat,

Thanks for the photo, that is the blade I have been using but had not ground the radius as you have so I'll give this a try. Also just set up my new QCTP, 100 series, so I will utilize the parting tool holder that came with the set. Does the angle that your tool holder presents the blade to the work impact + or - using that QCTP configuration? I see that rear tool post as interesting and a nice project with practical use but it will not fit to my Atlas so will save it for a future lathe.

Peter N
01-31-2009, 10:40 AM
Ah but but we weren't talking about Tool & Cutter grinders Norm, I think the discussion was more along the lines of parting off blades :D

Of course these days 50 is nothing really, about what I spend on a Chinese takeaway for the family, and with the same carbide insert having been in there for about a year or more now, even more of a bargain.
You don't have to be sad and sorry all in one post Norm, and despite the cost of flags in China you can't accuse them of being guilty of neo-Luddism ;)

Peter

Norman Atkinson
01-31-2009, 12:43 PM
The subject WAS a 5/8th Parting tool blade held by somebody who found it necessary to fling the whole lot into the (Roman) Forum to be torn to bits
( Well metaphors and whatsits permitted) The blade was HSS and not carbide and unusually for me, I kept to the question( at the beginning, anyway)
<Wait for roar from the Plebians>

Now Peter, I could have been naughty and got unfrocked or worse for suggesting that he could have made a tool and cutter grinder from plastic( err uhm). Instead, I gave a thoroughly good economics argument of what in the year of our Lord 2009 what the economic choices were- TWO parting off tools ( Minus holder) and an all singing whatsit which would sharpen every tool in the armoury until the end of time. It was more or less conditional that the guy would accept HSS ( which he had).

OK - Peter, you remind me of Huskisson- no, that was a train but that, if my economic history class continued next week would go to Brighton- and Red Flags abandonned.( that's the history- fellas- of Reckless Speed)

So 50 eh? for all those poor, starving children! Peter, my friend, I could have got 19(yes) courses at the start of the Year of the Ox for 16 a head- of which 1 went to buy Teddies for Kids in Hospital.



Right off topic-- Kung Hei Fat Choy! But it does wish you all a happy(chinese) new year.

Ling_Sam Sam Yee_Say-Say

Norm

tornitore45
02-01-2009, 12:51 PM
We've been through all this before and before.

The classic answer is to use a rear tool post and run the lathe forwards but using a tool inverted at a 7 degree slope. Set at exact tool height, of course.

The top of tool remains straight but has a convex grind along it. The recommended grind is a vee of 140 dgrees but I found a simple curved female grind( calm down, fellas) was enough. The front of the tool had a male 140 degree vee'd edge.

Norman

Norman, let me see if I understand you description.

7 degree slope mens that the bottom surface of the inverted toll present a positive 7 degrees rake, right?

The word convex and female puzzle me. W are still talking about the bottom surface of the tool. Convex, to me, means that the V looks like a house roof not a V groove. Female, means (i think) hollow in the center, in this case a groove or a arched though ground lenghtwise. Right?

As for the tool front I understand a male V to resemble the stern of a ship.

Please clarify thanks

Mauro
In Austin TX

Norman Atkinson
02-01-2009, 01:32 PM
I would agree that it is difficult to comprehend. Bit like being avalanched and having to spit!

OK- lets do the blade itself.
Along the top of the blade( about an inch) is a female vee of 140 degrees or a curve( from a worn slitting wheel) Female is female- going into as in a con-cave.
The front of the tool has a male chamfer of 140 degrees- male to go out and into over or when one is vexed- you go out. ( Sounds a bit but that's the way of the World)

The tool is inclined at 7 degrees to the work( at centre height)
If you think- you don't need to put a back rake on the tool because it is inclined. So all that a re-grind needs is a tiny bit of grinding off at the front.
Actually, it is simply a normal cutting tool. You could use a flat topped lathe tool in the rear tool post- instead of grinding back rake.

I hope that that is clearer.

Why not E-mail me at Norman@n-atkinson.wanadoo.co.uk
In truth, it is easier to draw than write about.

tornitore45
02-01-2009, 05:23 PM
Thanks Norman, much clear now.
Exaggerating the idea, the tool act as a scoop.
I am using now a T blade on a home made rear post with no agle because it has no height adjustment to compensate for different protrusions.

Even witgh a simple flat tip, zero rake, it works well on my Chinese 9x20 but I am always open to improvement particularly if this is a old technique validated by time.

Agree, drawing is the language of geometry, words are a poor tool for shapes.

Mauro
In Austin TX

Spindle
02-07-2009, 11:30 PM
Weeeeeeeeeeeeeell that clears that up..... But seriously- it seems like the HSS and carbides have their respective advantages and disadvantages. Plenty of reasons to have both.
I'll be back with many more questions.

Dave P.
02-08-2009, 12:06 AM
I chose the one already mentioned, from ENCO, the Newcomer. With getting the kit, you'll get everything ready to use with your new QCTP including 10 of the inserts. Get one that takes the narrow inserts, it is much easier on your lathe -- in the Newcomer its .087. Heres the one I chose ---
http://www.use-enco.com/CGI/INSRIT?PMAKA=422-2914

As mentioned, its qualifies for free frt, too;) --- use code PRPT12 (that'll expire end of the month...)

Going back in time a few days.....
Bill,
What's the max reach with that setup?
Thanks
Dave P.

Spindle
02-08-2009, 08:04 PM
Click that enco link, the resulting page will have a link to Master Catalog page 188, blade cutting depths are on a chart at the bottom of that page.

lazlo
02-08-2009, 09:55 PM
I think I'm dangerously over my "Piss off Norm" limit this week :), but I have to agree with BadDog, Peter et al: I have the Sandvik parting tool system, and it's fantastic. I think the reason it works so well is because the nose is shaped like a chute that flares outwards: it curls the chip away and up from the workpiece, minimizing the cutting forces.

Like Norm describes, Geo Thomas shows some fancy cutting tip geometries to minimize parting forces, but there's no way a home-shop guy could make the curved 3D nose shape on the Sandvik, Newcomer, et al parting tips.

Now, along those same lines, Sandvik also has a very cool slitting/slotting saw that uses the same inserts: basically picture 8 of the parting inserts mounted radially on a milling arbor. I just got this in last weekend, and I've been cleaning the Excello since, but I'm dying to try this on some 4140 Pre Hard:

http://i164.photobucket.com/albums/u15/rtgeorge_album/IMG_0049.jpg

ACF
02-09-2009, 08:44 AM
Lazlo,

As well as those carbide parting tools work, that blade you have there with the 8 inserts, ought to be one badass metal moving monster!!!!

Chris

fdew
02-09-2009, 09:50 AM
I have been following this carfully. I need a cutoff tool (Ihave been using a home ground HSS 1/2 tool bit.) My lathe came with a Aloris holder AXA7 that is designed for T shaped cut off blades. I am going to start with that, knowing that some day I will want to move up to a carbide system. My question,

What assortment of widths do I get? I can go from .040 to 1/8 I am liiking at the Enco USA blades.

I will be cutting cast iron and steel up to 2 in thick

Thanks