Lathe tool holder?

[flyman219]

Here I am again with another beginner question. I have got my HF 8x12 on the bench and running now and noticed the tool holders that came with the used machine are to big for the square cutter rest. My rest can take about 3/8-1/2" and I was wondering if I could just grind down the top side of the 1/4" tool holder to 1/2". Or, would I be better off just getting some indexable 3/8" cutting tools and not bother with the tool holder. I'm looking at the 5 piece 3/8" set that Littlemachineshop has for about $33. I also got a quickchange tool post with the lathe that will accept the 3/8" cutter bits. Thanks for your time
Mike

[mxtras]

Cutting tools are expendable. I do whatever I need to do - especially to the shank of the tool to allow them to work in the equipment. I have milled the shanks of insert tooling to allow them to fit into the holder numerous times.

I have even cut the insert end of an indexable holder, milled in an angle and welded it back to the shank to create a more positive rake from an insert that was more neutral than I cared for.

Scott

[jrrdw]

I got the HF 8X12 also. I got myself 15, 5/16ths HSS cutting bits from Enco, model number: 383-5320. I grind about half off the shank, then a little off of another one and stack them on top of each other and clamp the down. My lathe came with a 4 post bit holder, i like it! I've allready ground a few different shaped bits, one for o-ring grooves, one for parting/facing/left angle/right angle. I even went to the hardware store and bought a 3/8ths" X 12"s long piece of steel stock and ground one corner off 5"s long, then down the left side for part clearance. I use it to trim out/true sealing faces on pneumatic valves. It's funny looking to see a foot long cutting bit on my lathe.

[flyman219]

Thanks for the help, I'm going to grind down the tool holder so it will fit in the tool rest. Next question, the tool holder has the 1/4" bit set in it at a angle rather than horizontal to the work. Is there any threads on the forum that shows what kinds of angles are needed to sharpen the bit. I've seen the angles for the bits that mount dirtectly in the tool rest but not with a bit in a tool holder, left, right, straight etc.
Mike

[in2steam]

Originally Posted by flyman219 Here I am again with another beginner question. I have got my HF 8x12 on the bench and running now and noticed the tool holders that came with the used machine are to big for the square cutter rest. My rest can take about 3/8-1/2" and I was wondering if I could just grind down the top side of the 1/4" tool holder to 1/2". Or, would I be better off just getting some indexable 3/8" cutting tools and not bother with the tool holder. I'm looking at the 5 piece 3/8" set that Littlemachineshop has for about $33. I also got a quickchange tool post with the lathe that will accept the 3/8" cutter bits. Thanks for your time Mike

You know you can buy HSS, and its the right size already, although may need to shim it up depending upon your grinding skills.

chris

[jrrdw]

Originally Posted by flyman219 Thanks for the help, I'm going to grind down the tool holder so it will fit in the tool rest. Next question, the tool holder has the 1/4" bit set in it at a angle rather than horizontal to the work. Is there any threads on the forum that shows what kinds of angles are needed to sharpen the bit. I've seen the angles for the bits that mount dirtectly in the tool rest but not with a bit in a tool holder, left, right, straight etc. Mike

I would sharpen the bits the same way no matter what tool holder your useing. When it comes to shaped cuts, grind the bits acordingly.

I like this smily

[widgitmaster]

Here is a little image depicting the various types of lathe tool bits, and their model numbers.

I agree, I make my own tool bits, and tool holders to suit the situations for the parts I'm making. Not all tooling is the same, as different materials require different tool geometry. You need to learn the difference between Positive, Negative, and Neutral Rake. As crystalline materials like brass & bronze require a positive rake, where copper & soft aluminum use a negative rake.

Tools with a sharp point will leave a rough finish, and a slight radius will improve the finish and allow for faster federates. THere are several books available such as Machine Tool Technology ISBN 0-02-671570-8 that cover lathe tool geometry in great detail!

Widgit