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viking
02-17-2008, 05:20 PM
I need to machine the T-slot for the tool post on a 1/12 scale mini lathe project I am working on. I assumed I was going to use a woodruff key cutter for this however looking at the specs. on them even the smallest is 1/4" dia. Way too big. The slot for the tool post needs to be .188 x .070 and .156 at the skinny part of the T-slot. Obviously the .156 part is a straight forward milling job with common tooling but what is available to mill out the .188 X .070 part at the bottom. The length of the T-slot is approx. 5/8" and it is aluminum.

I have thought of some solutions but none that seem practical. Any ideas anyone?

SGW
02-17-2008, 05:26 PM
My first thought would be to make a cutter out of drill rod. You could probably file out the teeth (maybe 4), and harden. If it's just going to cut a slot 5/8" long in aluminum, it doesn't have to be a great cutter, just something that works.

howiesatwork
02-17-2008, 05:26 PM
Make and heat-treat a custom cutter. Mini-tools for mini-projects...

Al Messer
02-17-2008, 05:26 PM
Check the tools available for Dremel and similar tools. They have some that are very small indeed.

Bguns
02-17-2008, 05:26 PM
Make an L shaped single point tool and shape each side of slot. You could use carriage on lathe with work on a face plate,

Another idea is to get that .250 woodruff cutter and grind it down to .188 and cut new relief angles.

Go easy not much room for aluminum chips....

LastOldDog
02-17-2008, 05:54 PM
I need to machine the T-slot for the tool post on a 1/12 scale mini lathe project I am working on. I assumed I was going to use a woodruff key cutter for this however looking at the specs. on them even the smallest is 1/4" dia. Way too big. The slot for the tool post needs to be .188 x .070 and .156 at the skinny part of the T-slot. Obviously the .156 part is a straight forward milling job with common tooling but what is available to mill out the .188 X .070 part at the bottom. The length of the T-slot is approx. 5/8" and it is aluminum.

I have thought of some solutions but none that seem practical. Any ideas anyone?

Start with a 3/16" (.1875) two flute end mill, place it in a spindex, go to the grinder, move up only enough to clear the top surface of you workpiece, reduce the dia to something slightly less than the .156" you need to clear the slot. Lay it out on paper to confirm dimensions and clearances. In effect, you have created a 'T" slot mill from an off the shelf item.

darryl
02-17-2008, 07:49 PM
What LOD said- my first idea was to convert a drill bit for the job. You will need to cut the fluted part shorter (start with a drill that's shot already) and use a toolpost grinder to narrow the shank where it needs to be. Pay attention to the thickness of the web as you create this new cutter. I've long been wondering what disc should be used when squared corners are desired for a job like this- similar to grinding a smaller diameter pilot on the end of a drill bit-

At any rate, if you can TPG you can make the cutter easily enough.

Oldbrock
02-17-2008, 08:04 PM
<a href="http://s273.photobucket.com/albums/jj232/brockley1_bucket/?action=view&current=January07snowsofar29th002.jpg" target="_blank"><img src="http://i273.photobucket.com/albums/jj232/brockley1_bucket/January07snowsofar29th002.jpg" border="0" alt="dremel flex shaft set to neck cutter"></a> I'm new to photobucket so hope this comes through. Dremel flex shaft end mounted in toolpost and cutter in chuck. You can neck the cutter down this way. Peter

Oldbrock
02-17-2008, 08:10 PM
http://i273.photobucket.com/albums/jj232/brockley1_bucket/January07snowsofar29th002.jpg the picture could come through this time

LastOldDog
02-17-2008, 08:16 PM
What LOD said- my first idea was to convert a drill bit for the job. You will need to cut the fluted part shorter (start with a drill that's shot already) and use a toolpost grinder to narrow the shank where it needs to be. Pay attention to the thickness of the web as you create this new cutter. I've long been wondering what disc should be used when squared corners are desired for a job like this- similar to grinding a smaller diameter pilot on the end of a drill bit-

At any rate, if you can TPG you can make the cutter easily enough.

Darryl, good follow-up, thanx, I did omit the part wherein the end mill would be shortened 'to the max' to reduce overhung load and potential chatter.

Additionally, the upper cutting surface on this special ground "T" slot cutter, should likely be stoned a little to provide clearance.

viking
02-17-2008, 08:18 PM
I mounted my Dremel on the toolpost and it only took minutes to reduce the shank of a 3/16 endmill to below.156 . I covered the ways and sprayed souluble oil from a squirt bottle to preserve the heat treat of the endmill.

http://i2.photobucket.com/albums/y26/chiliviking/DSCN2718.jpg

Thank you to everyone that responded to my request. In less than 30 minutes my T-slot was completed.

Oldbrock
02-17-2008, 09:02 PM
Way to go. Glad to help, that's what this site is all about. There is always someone out there who has been there and done that. Peter