Using a collet block with a mini-mill

[ARC-170]

I'm making a cylindrical part that will require the use of a collet block because I have to mill a slot on the end, then drill and tap a hole perpendicular to the slot. My vise jaws are 1" high. This seems like it will not adequately support the work standing on end. So, I'm thinking I'll need to clamp the collet block to a right-angle fixture (properly aligned) for the slot, mill the slot, then rotate the block, re-clamp it to the right-angle fixture, and drill the hole.

Anyone ever done an operation like this on a smaller mill? Is my thinking sound/safe? I have an LMS 3990 mill.

 

[mickri]

What is the diameter of the part and how long is it. What type of collet block are you using? 4 sided, 6 side or ???? A 4 sided block would probably work best for what you are trying to do.

You could have the work horizontal instead of vertical. Mill the slot then rotate the work 90 degrees and drill and tap the hole. If the bottom of the slot needs to be flat you could then use a file to make the bottom flat.

 

[ErichKeane]

What does your part look like? Have you considered using a slitting saw to cut the slot? That way you could make the slot with it laying down, AND cut/tap the hole in the same operation.

 

[C-Bag]

Wouldn’t a v block do what you want to hold it vertical and horizontal?

 

[ErichKeane]

Wouldn’t a v block do what you want to hold it vertical and horizontal?

i think his reasoning for the collet block was that he needs to do 2 operations at 90 degrees to each other. If you swap with a V-block from vertical to horizontal, you end up having to re-align the result of the 1st operation to be 90 degrees to the 2nd. A collet block allows the setup to be consistent and correct.

That said, doing this in 1 setup seems best ot me

 

[JimDawson]

I'll need to clamp the collet block to a right-angle fixture (properly aligned) for the slot, mill the slot,

I see no problem with what you propose. Clamping to an angle plate is a good way to hang on to the collet block for the milling operation. Then lay it down in the vice, or just clamp it to the table for drilling the cross hole.

 

[higgite]

I won’t speculate on why you need to mount the cylinder vertically to mill the slot, but will offer an alternative to a right angle fixture. If you mount the cylinder in a collet block or V-block, can you mount it vertically in your vise and mill the slot on the Y-axis? That will give much more support to a vertical work piece than slotting on the X-axis will. Then just lay it over horizontally in the vise and drill the hole.

Tom

 

[C-Bag]

I’ve done such operations when I made a tool holder and it’s why I decided against the usual Kurt vise and went with a CNC style vise which is just a bigger tool makers vise. You can lay it on it’s side which you can’t do with a regular I’ll vise. I’ve also got a 2” and 1” toolmakers vise. Also small v blocks. So far they have done what I’m not sure a collet block could have done in my circumstances. But YMMV.

 

[ARC-170]

Here is what I'm making. It's a project in the Beginning Machining class I'm taking.



The slots need a flat bottom. There are also flats to machine. The instructions call for standing the part up vertically to machine the slots, then lay the part down and mill the flats and drill the holes. All straightforward if you have the proper tooling. The instructions call for a C5 collet to be put in a collet block. I don't have one, but could probably borrow one. I thought of making a collet block for the R8 collets I have, since no one seems to sell them. The machines at the adult school or full-size Bridgeports with full-size vises, too. I have a small LMS 3990 mill and a small vise.

To give you a better idea of what I thought I would do, here is a picture. I have placed the R8 collet in the proper position for milling the slot. You'll have to imagine it being held by a collet block and being properly clamped. The angle bracket is about 2-1/2" high, so should provide enough support. I would just rotate the collet block 90 degrees to make the holes and flats. You can see that my vise is not very big.

 

[mickri]

This is how I would do it. I would scribe lines on the end of the work that are perpendicular to each other. To do this I would mount the work in the vice and then find the center of the work. I would put a scribe in the mill and use it to make the lines. I would then mill the slot. Reposition the work to being horizontal in the vice so that the line that is perpendicular to the slot is now vertical. Then dill and tap your holes.