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mattthemuppet
10-14-2013, 03:06 PM
and I'm not talking about explaining the value of indexable cutters to the wife :)

I finally ground my first boring bar from a HSS blank and it works beautifully, even on steel. But I couldn't figure out the best way to use it. Am I supposed to start at the mouth of the bore and cut a constant depth towards the headstock? Or should I use it like I'm facing the work, starting a fixed distance inside the bore and increasing depth of cut radially?

I was cutting a relief on the back of my new chuck so that it would thread onto the lathe spindle properly and register properly, so I only needed to cut perhaps 1.5mm towards the headstock (ie. into the chuck) and 2mm radially. I don't have any measurement devices at all on the lathe yet (working on that though) so I could only tell when I'd cut a pass to the correct depth by ear as the sound would change from a sssss to a squeak. Got it done eventually, but it took a while!

What I need to do some time in the future is bore two 14mm deep by 20mm wide holes in a lump of alu. Do I drill to approximately the right depth then bore longitudinally from that hole or is there a better way of doing it? This is all completely new to me, so some way of skipping at least a few of the screw ups would be neat :)

thanks!

Dr Stan
10-14-2013, 03:13 PM
start at the mouth of the bore and cut a constant depth towards the headstock

What I need to do some time in the future is bore two 14mm deep by 20mm wide holes in a lump of alu. Do I drill to approximately the right depth then bore longitudinally from that hole or is there a better way of doing it? This is all completely new to me, so some way of skipping at least a few of the screw ups would be neat :)


thanks!


This is the correct approach

Rough in the holes with a 17 or 18 mm drill bit to depth. Then take an end mill of the same diameter to flatten the bottom, preferably a single end 2 flute EM.

Tony
10-14-2013, 03:24 PM
that infamous squeak or squeal is always a reliable sign that you've reached the bottom :)

I'm sure everyone's got their way of doing it but I like to (in no particular order)
1. mark the depth on the boring bar itself.. with a sharpie, for example. maybe 0.020" or so shy from the bottom
that'll at least give you a visual.

2. use a carriage stop. if you don't have one use a beefy c clamp. :)

3. if the hole isn't so deep that you must use your carriage (or carriage feed).. there are always the
divisions on your top slide. if its deeper, then use the above tricks to get within 5-10-20 thou, measure,
then clean up the bottom using your top slide graduations.

better yet, if its really important, rig up a dial indicator against your carriage somewhere to clean up
those last few thou.

wait.. does no measurement devices on the lathe mean no divisions/graduated dials?

Richard P Wilson
10-14-2013, 03:46 PM
[QUOTE=mattthemuppet;879841] distance inside the bore and increasing depth of cut radially?

I was cutting a relief on the back of my new chuck so that it would thread onto the lathe spindle properly and register properly, so I only needed to cut perhaps 1.5mm towards the headstock (ie. into the chuck) and 2mm radially. sound would change from a sssss to a squeak. Got it done eventually, but it took a while!

1.5mm isn't very deep for a chuck backplate register, most spindle registers are at least 1/4" (6mm) long. What lathe have you got? Any chance of a photo?

Richard

mattthemuppet
10-14-2013, 03:55 PM
This is the correct approach

Rough in the holes with a 17 or 18 mm drill bit to depth. Then take an end mill of the same diameter to flatten the bottom, preferably a single end 2 flute EM.

that's an interesting approach, I hadn't thought of that. Only downside would be that I don't have a tail stock that I can put a drill chuck in, although I'm working on a ghetto milling attachment that I can make to hold one. If I used a large drill, do I still bore to the correct diameter with the boring bar, before finishing the bottom with an end mill?


that infamous squeak or squeal is always a reliable sign that you've reached the bottom :)

I'm sure everyone's got their way of doing it but I like to (in no particular order)
1. mark the depth on the boring bar itself.. with a sharpie, for example. maybe 0.020" or so shy from the bottom
that'll at least give you a visual.

2. use a carriage stop. if you don't have one use a beefy c clamp. :)

3. if the hole isn't so deep that you must use your carriage (or carriage feed).. there are always the
divisions on your top slide. if its deeper, then use the above tricks to get within 5-10-20 thou, measure,
then clean up the bottom using your top slide graduations.

better yet, if its really important, rig up a dial indicator against your carriage somewhere to clean up
those last few thou.

wait.. does no measurement devices on the lathe mean no divisions/graduated dials?

great advice, especially marking the boring bar, thanks! Yes, no measurement devices means no graduated dials. No lead screw either, so a carriage stop doesn't help much either :) It's a very small old lathe - small as in it can sit on the passenger seat of my car, old as in the indeterminate age of the very old. Still, it's what I have! I'll be posting up a strip down + "refit" thread sometime soon, once I've got my digital tire gauge "DRO" set up...

Toolguy
10-14-2013, 03:57 PM
Once you have the flat bottom in the hole, put the boring bar inside the hole and bring it to just touch the side of the hole. Then back out and dial a few thou. for the first cut and zero the dial or DRO. Make a cut starting from outside the part and feeding toward the chuck. Measure the newly bored hole, move the difference and make a finish cut. Depending on how much material needs to be removed, you may have to bore several times in small increments to get to the finish size. Always use the shortest stiffest boring bar that will do the job. A set of brazed carbide ones is not that much and works great on most projects. Plan on sharpening them yourself as they wear with a green wheel or diamond wheel.

mattthemuppet
10-14-2013, 04:00 PM
1.5mm isn't very deep for a chuck backplate register, most spindle registers are at least 1/4" (6mm) long. What lathe have you got? Any chance of a photo?

Richard

I do, it's kinda embarrassing though:

http://i1349.photobucket.com/albums/p752/mattthemuppet/IMG_1622_zps7419abe3.jpg

(it's an old picture, so I don't use that file on the lathe anymore)

here's the spindle, although for some reason I didn't remove the adapter plate

http://i451.photobucket.com/albums/qq237/pinkarella_photos2/Matts%20boring%20stuff12/IMG_1739.jpg

the whole spindle nose including threads is about 20mm long, give or take

Martin0001
10-14-2013, 04:14 PM
1. Drill about as deep as needed.
2. Use bigger drill (this might save time.
3. Expand hole as needed.
On my 3 1/2 inch ML7 lathe my routine with carbon steel is, after center drilling use initially 13 mm drill, then 22 mm drill (this is highest diameter available on MK2 taper) then bore to size.
Of course there are *smaller* bores as well but imho anything worth boring must be wider than 13 mm.
Smaller holes are just drilled & reamed.

Hint.
For final cuts sharpen your boring tool or put in sharp carbide insert, or your bore will be tapered.

Boucher
10-14-2013, 04:17 PM
For shallow cavities, I often find it easier to use a facing cut than a boring bar.

Tony
10-14-2013, 04:26 PM
fyi no lead screw required for carriage stop. in fact its better as you have no nut to strip. :)

imagine just using a c clamp on your rails.. gives the carriage something to crash into before it gets
to the bottom of the bore.

might look something like this:
1. lathe off
2. touch tip of boring bar / drill / reamer / etc to face of your work.
3. measure, say, 1" down your ways and clamp a block of something there. brass/alum/steel.

now your tool can't bore a hole deeper than 1" because your carriage can't physically get it there.

mattthemuppet
10-14-2013, 04:28 PM
Once you have the flat bottom in the hole, put the boring bar inside the hole and bring it to just touch the side of the hole. Then back out and dial a few thou. for the first cut and zero the dial or DRO. Make a cut starting from outside the part and feeding toward the chuck. Measure the newly bored hole, move the difference and make a finish cut. Depending on how much material needs to be removed, you may have to bore several times in small increments to get to the finish size. Always use the shortest stiffest boring bar that will do the job. A set of brazed carbide ones is not that much and works great on most projects. Plan on sharpening them yourself as they wear with a green wheel or diamond wheel.

thanks for the tips! I can't make deep cuts with this lathe as it only has 1/6hp motor (!), so it just stalls, plus the amount of flex and backlash in the cross slide/ compound doesn't help. Multiple shallow cuts it probably the way to go. I tried a brazed carbide bit, but either it was crap or my lathe doesn't spin fast enough for it to work. HSS or the cheap indexable cutters I got for Christmas seem to work really well though.


1. Drill about as deep as needed.
2. Use bigger drill (this might save time.
3. Expand hole as needed.
On my 3 1/2 inch ML7 lathe my routine with carbon steel is, after center drilling use initially 13 mm drill, then 22 mm drill (this is highest diameter available on MK2 taper) then bore to size.
Of course there are *smaller* bores as well but imho anything worth boring must be wider than 13 mm.
Smaller holes are just drilled & reamed.

Hint.
For final cuts sharpen your boring tool or put in sharp carbide insert, or your bore will be tapered.

Never thought about it like that, makes sense though and it'll be a whole (see what I did there?!) lot quicker too. Resharpening prevents tapers because the cutter won't be pushed out of the cut?


For shallow cavities, I often find it easier to use a facing cut than a boring bar.

thanks, that's pretty much what I ended up doing.

Still, with all these tips I should be able to pick the best set of tools/ approaches for a particular job. I'm learning as I go, but some stuff I just don't know that I need to know it!

Martin0001
10-14-2013, 04:59 PM
Never thought about it like that, makes sense though and it'll be a whole (see what I did there?!) lot quicker too. Resharpening prevents tapers because the cutter won't be pushed out of the cut?

That is a reason.
Final cuts (for example last 2-3 mm) always with sharp tool.
Otherwise there will be a taper, a considerable one.

Finally:
Resharpen and hone tool before last few thous cut - that makes all the difference in terms of surface finish.

mattthemuppet
10-14-2013, 06:14 PM
fyi no lead screw required for carriage stop. in fact its better as you have no nut to strip. :)

imagine just using a c clamp on your rails.. gives the carriage something to crash into before it gets
to the bottom of the bore.

might look something like this:
1. lathe off
2. touch tip of boring bar / drill / reamer / etc to face of your work.
3. measure, say, 1" down your ways and clamp a block of something there. brass/alum/steel.

now your tool can't bore a hole deeper than 1" because your carriage can't physically get it there.

now I understand :) that's a really neat tip, thanks! I could even just clamp the cross slide (ooh, a new project) as long as I have enough clearance with the carriage to advance into the work. Hmm, thinking now...



Finally:
Resharpen and hone tool before last few thous cut - that makes all the difference in terms of surface finish.

does a faster spindle speed also help? I've been doing most of my turning at the lower of the 2 speeds, otherwise the tool sometimes seems to "skate" over the material. I've read that higher speed = better finish.

vpt
10-14-2013, 07:04 PM
For shallow cavities, I often find it easier to use a facing cut than a boring bar.


I agree!

You want more fun, locate and cut a groove for an internal O-ring.

http://img849.imageshack.us/img849/5379/hydraulicram018.jpg

Martin0001
10-14-2013, 08:19 PM
Speeds and feeds are best to be found experimentally because not all what books say will work exactly as specified on your particular machine.
Too many factors at play.
I am finding it easier to get nice finish on internal bore than on external bar turning.
Carbon steel doesn't like high speeds too much.
I would stay with lower speed and finer feed but you must check it yourself.

Toolguy
10-14-2013, 08:24 PM
Also, to avoid chatter, put the cutting edge of the boring bar a little above center. Then when it bends down it will be moving away from the part. If on center when it bends down it will dig into the part.

Dr Stan
10-14-2013, 08:35 PM
Well I'm glad I do not have any pics of the "wood lathe" I rigged up one time using some cheap die cast bearings a 2X4, some sort of electric motor, a couple of pulleys, a V belt and a screw on drill chuck. Your lathe is far superior to what I had at the time, but it did the intended job.

One of those necessity is the mother of inventions situation.

spongerich
10-14-2013, 08:48 PM
I tried a brazed carbide bit, but either it was crap or my lathe doesn't spin fast enough for it to work. HSS or the cheap indexable cutters I got for Christmas seem to work really well though.

HSS is definitely the way to go for that small lathe. I have an SB 10K and even with that much larger machine, I've found that the higher tool pressures needed by carbide make getting a good surface finish more difficult. The only time I use carbide is when I'm cutting something especially hard. It's hard to beat a nice sharp HSS tool for most home shop lathes.

mattthemuppet
10-14-2013, 09:10 PM
I agree!

You want more fun, locate and cut a groove for an internal O-ring.


umm, err, perhaps not just yet :)


Speeds and feeds are best to be found experimentally because not all what books say will work exactly as specified on your particular machine.
Too many factors at play.
I am finding it easier to get nice finish on internal bore than on external bar turning.
Carbon steel doesn't like high speeds too much.
I would stay with lower speed and finer feed but you must check it yourself.

thanks Martin. I'm just beginning to get a feel for what works and what doesn't. So far the abilities of my machine far exceed my own, although hopefully one day that will change!


Also, to avoid chatter, put the cutting edge of the boring bar a little above center. Then when it bends down it will be moving away from the part. If on center when it bends down it will dig into the part.

ahh, that explains a problem I was having with it digging in. I also think that there's too much flex to use any top relief on my bits - I ground a cut off bar that was terrible until I reground the top flat, then it worked a treat. HSS grinding is a whole 'nother skill to master.


Well I'm glad I do not have any pics of the "wood lathe" I rigged up one time using some cheap die cast bearings a 2X4, some sort of electric motor, a couple of pulleys, a V belt and a screw on drill chuck. Your lathe is far superior to what I had at the time, but it did the intended job.

One of those necessity is the mother of inventions situation.

I am indeed very grateful for what I have. Before this, everything I made (mostly bike lights for night riding) was made with hand tools and a dremel. Although the end products work just fine, having a real life machine tool massively expands what I can do. I've been mentally planning my next light for about a year, since my friend gave me this lathe, but I have a few more little projects to practice on first as it's a worryingly ambitious project for me.


HSS is definitely the way to go for that small lathe. I have an SB 10K and even with that much larger machine, I've found that the higher tool pressures needed by carbide make getting a good surface finish more difficult. The only time I use carbide is when I'm cutting something especially hard. It's hard to beat a nice sharp HSS tool for most home shop lathes.

thanks! I find a great deal of pleasure in grinding a bit and then seeing it actually work. I bought a couple of arkansas stones for honing the bits and that seems to make the world of difference to how well they work.

mattthemuppet
10-14-2013, 09:11 PM
blah, double post

here's a few pics of what I've done with it so far

LED mini maglite for a cousin's Xmas present
http://i451.photobucket.com/albums/qq237/pinkarella_photos2/Matts%20boring%20stuff12/IMG_2333_zps07c3c474.jpg
http://i451.photobucket.com/albums/qq237/pinkarella_photos2/Matts%20boring%20stuff12/IMG_2354_zps350cb09d.jpg
http://i451.photobucket.com/albums/qq237/pinkarella_photos2/Matts%20boring%20stuff12/IMG_2359_zps8ae75f9d.jpg

mattthemuppet
10-14-2013, 09:18 PM
LED camping lantern conversion
http://i451.photobucket.com/albums/qq237/pinkarella_photos2/Matts%20boring%20stuff12/IMG_1624.jpg
http://i451.photobucket.com/albums/qq237/pinkarella_photos2/Matts%20boring%20stuff12/IMG_1633.jpg
http://i1349.photobucket.com/albums/p752/mattthemuppet/IMG_2617_zpse32259d8.jpg

vpt
10-14-2013, 09:26 PM
Nice job! I love the lantern!

mattthemuppet
10-14-2013, 09:44 PM
thanks! that heatsink/ pedestal was the very first thing I ever machined :) The light runs off 18650 li-ion cells salvaged from laptop battery packs and has a built in USB charger, so I can recharge it from the car 12V socket when camping. Makes for a good emergency lantern too, considering the 30 or so spare cells I have in the veggie draw in the fridge :D

Richard P Wilson
10-15-2013, 03:26 AM
Thats a nice little lathe of the precision bench lathe type, and worth money to guys who are interested in that sort of thing. When you upgrade to something bigger and stronger, it would be worth keeping the little one to do small parts. Have you checked out the www.lathes.co.uk site to try and identify it?

Richard

Rustybolt
10-15-2013, 08:36 AM
silly Q - how do you bore?

I usually start out talking about myself.

mattthemuppet
10-15-2013, 11:25 AM
Thats a nice little lathe of the precision bench lathe type, and worth money to guys who are interested in that sort of thing. When you upgrade to something bigger and stronger, it would be worth keeping the little one to do small parts. Have you checked out the www.lathes.co.uk site to try and identify it?

Richard

well it definitely doesn't begin with a W, that's as far as I got working backwards on that sight. Lots of cool machinery and some of the older lathes (early Wades, for example) have a similar double cone spindle set up to mine. More searching will have to wait for another coffee later today :) The only history I have is that it once belonged to a tatooist who used it to wind the coils on his injectors, who then passed it to a chopper builder, who gave it to my friend who worked with him in a bike shop who then gave it to me when he moved west to Oregon. I'll have to ask Tommy the chopper builder who the tatooist was so I can ask him where he got it from. It's like researching a family history!

I've spent many hours stripping it down and rejigging it. The last thing I did was take apart the motor, clean and oil it, now it works much more smoothly. I'd like to make new captive nuts for the compound and cross slide as they have about 1/4 turn play each and will happily jiggle their way from the work if I'm not paying attention. Plenty of more fun left in her and I agree, I'll probably keep her if I get a bigger lathe (like a 9x20 or similar) at least until I can find someone who it'd be worth giving to.

Next project is to make a couple of little LED lights for my girls. My eldest (7) has been pestering me to help her build something so a mix of machining and electronics should keep her happy (heavily supervised of course).


silly Q - how do you bore?

I usually start out talking about myself.

ha! Just like me :)

Tor
10-15-2013, 03:55 PM
My eldest (7) has been pestering me to help her build something so a mix of machining and electronics should keep her happy (heavily supervised of course).


Ah, little ones interested in making things. Get them hooked now while the goings good. I am firmly convinced that one (at least very nearly) essential component to living a truly happy and fulfilled life is to be capable of doing practical things with the hands - and spending time doing that fairly often. Often saves a bundle on hiring experts to fix things to boot. Round about here in our family it seems between us we can do most things - and often wonder how other people survive (financially at a minimum) when things go wrong.

Other than initial supervision, you might be surprised how little watching is really required. At that age I was building treehouses 20' up entirely on my own and build a short ladder to get five feet up and onto a 6:12 roof in order to walk up it and get to the walkway around part of the fourth story of our house (that had a railing, but the rood did not - and I would creep to the upper edge and look over.

dp
10-15-2013, 04:33 PM
I made several heads/heatsinks for laser flashlights that were stepped inside to hold the lens, electronics, LED, etc. I used only an unmodified two-flute end mill as the boring tool once the initial drill-thru was out of the way. The end mill was held in place on a boring head in the tail stock. I used the adjuster in the boring head to set the hole diameter and also ensures the mill is perfectly aligned with the lath spindle. This creates perfectly smooth bores and 90 angles. It is critical to get the cutting surface exactly aligned horizontal and exactly on the spindle centerline. The round shape of the end mill has adequate clearance for the cut and you can select a diameter of mill that is most suitable for the job.

SGW
10-15-2013, 05:05 PM
To bore, I read aloud random passages from a book my great-great-grandfather wrote called "The History of the Second Advent Message." :D

To bore on a lathe....
Getting a truly flat-bottom hole is decidedly a non-trivial operation. If I'm boring a blind hole, I first drill as large a hole as I can, measuring such that the tip of the drill just reaches the bottom of what will be the finished hole. Then use a center-cutting end mill to flatten an area around the center point. Note that it won't be truly flat because end mills have a 2 degree recess angle on the end. Next I set up a boring bar and check where the carriage is when the boring bar reaches the bottom of the hole. I set a dial indicator to that point (generally I set it to 0.500 or something like that so the needle will go around a few times before it comes to the reading that matters).
I set the automatic carriage feed to something reasonable for boring, engage the clutch, and let it go. When the dial indicator needle starts spinning, I watch and anticipate when it will get to 0.500 or whatever my set value was. I find I can anticipate and disengage the feed within a couple thousandths of where I want to be.
Once the hole is bored, generally a few thousandths shallow, I carefully face off the bottom of the hole with the boring bar to get it as flat as I can.h

mattthemuppet
10-16-2013, 10:10 AM
Ah, little ones interested in making things. Get them hooked now while the goings good. I am firmly convinced that one (at least very nearly) essential component to living a truly happy and fulfilled life is to be capable of doing practical things with the hands - and spending time doing that fairly often. Often saves a bundle on hiring experts to fix things to boot. Round about here in our family it seems between us we can do most things - and often wonder how other people survive (financially at a minimum) when things go wrong.

I agree completely. I also get a lot of satisfaction from fixing stuff and preventing it getting chuck out as trash. I think that rubs off on the kids too, at least going by the pile of toys that needs fixing :) My eldest has always wanted to help with stuff, but she's only just getting to the age where she has enough sense and motor control for me to feel comfortable with it. Finding the time is always a struggle too.


I made several heads/heatsinks for laser flashlights that were stepped inside to hold the lens, electronics, LED, etc. I used only an unmodified two-flute end mill as the boring tool once the initial drill-thru was out of the way. The end mill was held in place on a boring head in the tail stock. I used the adjuster in the boring head to set the hole diameter and also ensures the mill is perfectly aligned with the lath spindle. This creates perfectly smooth bores and 90 angles. It is critical to get the cutting surface exactly aligned horizontal and exactly on the spindle centerline. The round shape of the end mill has adequate clearance for the cut and you can select a diameter of mill that is most suitable for the job.

hmm, interesting. I've read of people using end mills as boring bars, some even grind off one flute too. Thanks!



To bore on a lathe....
Getting a truly flat-bottom hole is decidedly a non-trivial operation. ...
Once the hole is bored, generally a few thousandths shallow, I carefully face off the bottom of the hole with the boring bar to get it as flat as I can.h

thanks SGW. Seems like a common approach is to drill to close to diameter and depth, rough out with an endmill (or even finish with one) and then take the finishing cut to the correct dimensions.

Looks like I need to find away to make an adapter for my tailstock that will allow me to put at the very least a drill chuck on there. I'll have to find some drill rod or similar, drill and tap a hole for the crank, cut a key way for the thing on the side that stops it rotating, then thread the nose for whatever I want to put on there. Some of that I can do on this lathe once I get the 4 jaw set up and everything aligned, but the drilling and keyway cutting I'll have to bribe the machinist at work to help me with as there's no way on earth I can drill a hole straight that long with a hand drill!