How to hold and drill 2 holes on a single diameter of a cylinder (thick tube actually)

[Larry$]

it's the rough stock. I should have turned the outsides while it was on the lathe

This seems problematic. If there is any variation in diameter, one of the parts will not be held well! Use the wiggler to find the location of the fixed jaw. Set you Y dial to zero. Move the vice in and use the wiggler to find the face of the movable jaw. Read diameter on Y axis dial. Move Y axis to the 1/2 diameter point, set dial to zero. Use wiggler to find edge of cylinder. Set X dial to zero. Move X table travel to the center of the cylinder based on the 1/2 diameter size Set X axis dial to zero. You can now offset the distance from center that you want to drill in both directions. Do a little math to find the locations of the holes on the other cylinder. IE find it's center by adding the diameter to the first cylinder's center. Zero the X-axis and do the same off sets for the two holes. How it would have been done in the good old days before DROs. I prefer an edge finder to the wiggler. I find them easier to use and quite accurate. They are pretty cheap. Though quite expensive, a DRO makes life much easier also.

 

[markba633csi]

Should be fine if the vise is square and trustworthy- make sure both pieces are held securely
Me, I would probably put a piece of crush between the movable jaw and the parts (popsicle stick, or thin cardboard)

 

[Jimsehr]

I think I would put soft jaws on the mill vice. Bore jaws in mill to part od . Now everything is perfectly true. Now move off center to center of hole needed. Then move back needed distance past center to drill other hole.

jimsehr

 

[dbb-the-bruce]

I prefer an edge finder to the wiggler.

I'm just being a little dense tonight - Yes agree, I use an edge finder. Started with the wiggler used it about 4 or 5 times. I forgot the name difference. Second - yes would have been best to find Y center off of the vice jaws. That was dumb mistake.

Differences in outer diameter was relatively small (was able to hold both securely in the vise - holes are only 1/8"). Next time around, I'd true up the OD on the lathe when boring.

put a piece of crush between the movable jaw

That's an excellent idea (as in obvious and I hadn't heard of it before) - I'll remember that for next time I have multiple slightly mismatched work or round stock between jaws.

Bore jaws in mill to part od .

This is also a good idea, however I've not yet had a positive experience boring on the mill. I've got a boring head with the set of braised carbide boring cutters, but have not been able to get a manageable cut when using them. I think it may partially be the lack of stiffness in my mill. My mill only has the quill handles (for a rapid, drill style feed) or a little tiny knob for a slower feed. It would be a real PIA to use that knob for a 2" deep bore.

I'm a lot more comfortable boring on the lathe with HSS and power feed. It still can be difficult getting it right. I need to check for some videos of boring on my class of machine (LMS HiTorque SX2.7). When I bore, at lower speeds everything want's to thrash around. Higher spindle speeds and the out of balance boring head vibrates the whole machine.

The only success I've had on the mill is very light cuts and feeds (and carbide likes heavier cuts?)

 

[Larry$]

The only success I've had on the mill is very light cuts and feeds (and carbide likes heavier cuts?)

I've got a set of those ultra cheap brazed carbide bars that came with my Chinese boring head. The boring head is OK. Not like the high quality ones but fine for the price. The brazed carbide bars work fine if I get them properly rotated in the head and keep them sharp. They will take very fine cuts and leave a very nice finish. I've made a couple of 3/4" boring bars with HSS tools and used them for interrupted cuts facing cast iron. Used in the horizontal position on the boring head. Really shows up any out of tram! I've also got a few longer inserted bars. They are more problematic because the inserts need to be taking a cut deep enough to get past the required depth of cut. Inserts made for aluminum work best or reground ones. I've used them on the mill with the head rotated to horizontal for deep holes. Take the time to see what works for what you have.

 

[markba633csi]

Surprisingly, I use wood quite a bit when milling (and even on the lathe too)
I fashioned a little T-shaped plywood table that clamps in my mill vise for drilling/milling small parts.
Small flat pieces can be fastened to it with c-clamps or sheet metal screws+washers

I also have a round, thick wooden "donut" for the lathe 4-jaw chuck that I fasten parts to for boring/drilling

 

[Larry$]

I use wood quite a bit when milling (and even on the lathe too)

I keep an assortment of wood and MDF around also. MDF to hold work above the rotary table to through drill into.

 

[dbb-the-bruce]

I've used them on the mill with the head rotated to horizontal for deep holes.

If my mill looked like that, I'd be boring on it!

 

[dbb-the-bruce]

just clamp the cylinder down on the machined face on the table

To vise or not to vise! I'm starting to have a complicated relationship with my vise.

I've been relying almost exclusively on my large vise, and it pretty much stays bolted to my table. My kit of table hardware is still lacking a bit in available nuts, bolts and tee nuts and I haven't gotten very proficient on setups that just use hardware and the table. The hold down kit I have seems like it's often too big for the work I'm doing.

In retrospect, planing this out a little better would have made things easier. I should turned the outside on the lathe and then I could have been more sure that the faces were true to the cylinder. At that point, just bolting them flat on the table and indicating the bore would have been easy. I pretty much ended up using the faces anyway.

I've also been learning that a large vise is not always better. Recently I was working a fixture plate and kept running into issues where my jaws are outside the range of my Y axis if I move them to the exterior front/back of the vise. Only 3 tee slots on the table, so the vise is pretty much stuck at one position. A smaller vise would have worked out better. I also have small precision vise that's bolted next to this one.

I need to pin or somehow make mounting the large one aligned so that I don't leave it mounted all the time. That and up my game with just bolting stuff to the table.

 

[markba633csi]

It's all good