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Paul Alciatore
02-19-2008, 10:45 AM
Here's some pictures of my latest project, well sub project actually. I was making a replacement for the vertical mount on my Unimat. You can see the original in one of the pictures with the crack it is developing at the attachment screw. Anyway, that is the original project. In order to finish the new mount, I need to bore a 25mm hole three inches through the mount. It needs to be parallel to three faces of the mount so I choose to do a line bore. Needed a special boring bar for this so that is the present project. In working out how to make the bar, I suddenly realized that the partially completed mount was the perfect way to attach the Unimat vertical column to my South Bend. I only needed to drill an additional 1/2" hole in the middle of the block to allow attachment to the SB compound. This would allow me to perform milling and drilling operations on work mounted in the SB with the added plus of indexing since my backplate has 60 indexing holes drilled in it. So here's the setup in operation milling a flat on the boring bar.

http://img.photobucket.com/albums/v55/EPAIII/P02.jpg

You can see the partially complete mount on the compound with the Unimat column on it. The hole that needs to be completed is to the rear in this picture and is presently drilled to 7/8".

And here's the same setup used for drilling.

http://img.photobucket.com/albums/v55/EPAIII/P09.jpg

After drilling the hole for the tool, I indexed the bar 90 degrees using the holes on the three jaw backplate and drilled a hole for the retaining set screw. Neat and sweet.

wschoenbeck
02-19-2008, 11:19 AM
Paul, That's a great idea for the Unimat. Now I have another project to build so I can use mine in that way. Thanks for the idea.

Al Messer
02-19-2008, 06:13 PM
Good job, and congratulations for using your noodle to overcome an equiptment limitation!

winchman
02-19-2008, 07:45 PM
Please tell us about the neat indexing holes on the backing plate of the chuck in the first photo. I can't tell if it's an add-on or made into the backing plate itself.

Roger

Paul Alciatore
02-20-2008, 01:15 AM
Please tell us about the neat indexing holes on the backing plate of the chuck in the first photo. I can't tell if it's an add-on or made into the backing plate itself.

Roger

I knew somebody would notice them if I left them in the picture.

The index holes are in the backplate itself. The three jaw that came with my lathe was a total wreck and runout was very bad. I tried grinding the jaws, but... When I purchased a new Bison three jaw, I designed a backplate that had four centering screws to imitate the true-adjust idea. So I can center the work as easily or even easier than in a four jaw. The six mounting screws have spring washers so when they are loosened the four set screws can easily position the chuck. They they are tightened again.

At the time I had easy access to a mill and I have a rotaty table so I decided to add indexing holes. There are 60 of them at six degree spacing. I took great care and about five or six steps to drill them: spotting drill, tap drill, main drill, reamer, countersink to debur. All of the above was done with new, good quality tooling and a single setup on the mill-drill. They were reamed to a final 3/16" diameter for 0.20" deep and there is a 4-40 female thread below that for another 0.20". I choose 60 as it provides a large number of usable divisions: 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, and 60 divisions. I miss the ability to do 25, 50, or 100 divisions but I plan to make some vernier sector plates some day to provide those and some other common numbers.

This is actually the first project where I used the dividing capability. It has shown me how valuable it is to be able to index work held between centers as well as just simpily being able to lock the rotation down for milling and drilling.

I have a new four jaw to mount and I plan to make a similar backplate with the same OD so my future sector plates will work with it also. I debated for some time over the idea of adding centering screws to a four jaw, but I finally decided it is a good idea. Yes, I can center work in a four jaw without this feature, but after using it on the three jaw I just knew it would be a strong plus on the four jaw also. You can rough center with the jaws and get them tight enough for the work and then use the adjustment screws to do the final centering. I am not an old timer so it appeals to me.

I have started an article for the magazines on the backplate with plans and pictures but have decided to let it wait until I do the four jaw and the vernier sector plates and also get some experience using it.

winchman
02-20-2008, 04:07 AM
That's a really good idea followed up with really nice work. Thanks for sharing.

Roger

Benta
02-20-2008, 09:09 AM
Paul, am I seeing things, or are you using a drill chuck to hold an endmill? :eek:

Benta

Carld
02-20-2008, 10:36 AM
Naw, he's using a drill chuck to hold a drill.

Paul Alciatore
02-21-2008, 01:01 AM
Paul, am I seeing things, or are you using a drill chuck to hold an endmill? :eek:

Benta

Yup.

I have a 1/4" collet holder for the Unimat spindle but wanted to use a larger mill so I wouldn't have to make 25 passes. I used a 5/8" cutter with a 1/2" shank. I know it is not recommended. And the runout was horrible. I took relatively light cuts. Total depth was only 0.050": three passes to 0.048" and one final cleanup to depth. I probably should have cut on the side of the cutter instead of the tip. I thought about that about half way through the job.

All I can say is it did work.