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Ryobiguy
10-21-2006, 01:20 AM
First some background:
Slowly but surely over the last two years I've been getting the 88 year old 13" South Bend lathe up and running, originally seen here with the rediculous compound damage: http://www.homeshopmachinist.net/bbs/showthread.php?t=5834

Since then, I have: repainted, replaced compound nut/leadscrew, re-motorized with 2hp vfd, gotten a 4 jaw chuck, quick change tool post, and some tools. Over time, I've gotten things tuned up a bit, and it finally feels like I can sort of do something with it.

Anyways, on with the point:
I've so far milled a couple of small things (like scrap .25" plate) that I could fit into the quick change toolpost holder and clamp w/ the set screws. But now I need to mill some bronze (new cross slide nut) that that wont fit into the quick change tool slot. Obviously I don't have a milling attachment.

I was looking at my old shop class made vise, thinking I could bolt it into the compound somehow, but that wasn't quite the right idea. What about bolting it onto something held by the holder on the quick change toolpost, since it has some height adjustment? I then discovered that I had just the perfect shape of L shaped scrap steel that could make this happen. So I drilled and counterbored the two holes required to make it go, a small enough investment to see what happens.

Here are the pics of the setup:
http://img.photobucket.com/albums/v129/Ryobiguy/LatheViseMount/8ViseMountedAngled.jpg
http://img.photobucket.com/albums/v129/Ryobiguy/LatheViseMount/7ViseMountedSide.jpg

I know this is going to lack any decent rigidity, and I think it looks funny enough to perhaps be amusing (is anyone laughing at me?) I havn't tried it out yet so I don't know if I'm an idiot or a hero; sometimes there's such a fine line between them.

Measuring deflection with an indicator, as I push down on the vise and lean on to it with perhaps 60-100lbs of force, the indicator sweeps up to about .007".

Think it'll work?

-Matt

torker
10-21-2006, 01:37 AM
Matt...aren't you a bit worried about that vise spinning out sideways?
I built a rotary fixture for my mill before I got a rotab. Had a three foot long handle on it to spin the alu block to make a semi circle. I was amazed at the force that a 3/8" endmill exerted on the far end of the handle. There was no way I could get a decent finish...just couldn't hold it still enough.
I'm thinking that vise may flex a bit also.
I did some milling with a drill press vise also. Had to drill it for a hold down bolt in the rear. The back end kept lifting. It was quite a bit stiffer than the vise you are using.
I'm thinking you may get away with really light cuts in alu but I'd have a catch net for the vise if it popped out :D
Russ

dp
10-21-2006, 01:50 AM
The hold-down screws should probably set into some shallow holes in the vice lug so it doesn't get cocked or shift. It could get pretty expensive and set back your restoration if that happens.

My friend Par in Sweden had to do something ugly to get the job done. Click here: http://uglytech.com/uglytech.nsf then click the little Swede flipping the bird, and follow the link to the throttle body work. He's building a Harley drag bike. In one step he needed to do some milling on a lathe.

winchman
10-21-2006, 06:03 AM
I wouldn't use that rig. It's got so much overhang that's it's going to vibrate like crazy, and you'll never get a decent surface finish. If you try to stiffen it up, you'll end up tearing out the topslide T-slot.

I hate to be negative, but I just think it's a bad idea.

Roger

JCHannum
10-21-2006, 07:37 AM
The overhang and vibration might be a problem. But very light cuts in brass with a small end mill might work if surface finish is not a major concern.

With all of these type milling attachments, overhang is a problem, it is the nature of the beast.

A better solution would be a heavy angle plate to mount the vise to. Removing the compound and mounting directly to the topslide removes one more source lack of rigidity. The topslide can be mounted to the angle plate to provide a vertical slide. I believe Evan did this with his milling attachment.

Ryobiguy
10-21-2006, 04:42 PM
BTW, great idea on the countersink/holes for setscrews to grab in to. I was sort of thinking of that too.

I've always wanted to get a beefy angle plate and mount the compound on it. That might be the next thing I eventually get.

OK, I found something to put under the vise in case of accident (big block of styrofoam,) tighened up the toolholder set screws until I felt comfortable, and went for it.

First I tried it with 5/8 endmill on steel at very slow RPM/feed/doc. This scared me quite a bit, but it sort of worked when the area being cut was very small (diagonal corner on some scrap round.) After a few passes at .002", it was just a bad idea. But, I had to (slowly and carefully) see what would happen with a light cut.

So then I moved to the bronze nut I'm making, which is 932 and 1.3" round. One end is .75" diameter for 1/4 inch length that fits in and screws into the same size counterbore on the bottom of the cross slide. I'm going to mount it up, then drill through it (the round side) for the lead screw while it's bolted in place so the alignment with screw should be pretty good.
Here's what the nut looks like in comparison to the current aluminum(!!) nut. Pic (http://img.photobucket.com/albums/v129/Ryobiguy/IMG_5141.jpg)
Here's the clearance problem: Pic (http://img.photobucket.com/albums/v129/Ryobiguy/IMG_5140.jpg)
Here's where I'm at right now: Pic (http://img.photobucket.com/albums/v129/Ryobiguy/IMG_5150.jpg)
Basically all I need to do with this flimsy milling setup is to make some side clearance on the part, to cut sort of a radius perpendicular to the round access that doesn't have to be round, accurate, or even look good.
I was wondering if I could use a bench grinder on the bronze (might need special wheel?) although that would have more of an ugly factor.

The 5/8 endmill seemed to dig in to the bronze and it was awful, so I switched to my "other" endmill (I don't mill much,) which is a 1/8" four flute. For this it seems OK, what a surprise, however at that rate it'll take forever!
Here's what it looks like, rule with 64th's for scale:
pic1 (http://img.photobucket.com/albums/v129/Ryobiguy/LatheViseMount/mill1.jpg) pic2 (http://img.photobucket.com/albums/v129/Ryobiguy/LatheViseMount/mill2.jpg) pic3 (http://img.photobucket.com/albums/v129/Ryobiguy/LatheViseMount/mill3.jpg)

Not the greatest of finishes, but better than I was expecting.
Even better and much more imporantly, all my body parts are intact and the ways are not damaged. :)

JCHannum
10-21-2006, 06:05 PM
If all you want to do is put flat sides on the nut. Chuck it sideways in your four jaw and face the sides.

IOWOLF
10-21-2006, 06:51 PM
Yikes!!!!!!!!!!!

C - ROSS
10-22-2006, 08:16 AM
I'm with the Wolf !!!!

Use the 4 jaw or just a vise and file.

Ross

Chuck U&R
10-22-2006, 09:32 AM
Would this setup be better if the vice was bolted thru the tool holder rather than using the slot ?

I'm having a dovetail milled into some bar stock to make my own BXA toolholders.
My plan is to chuck up a 3/8 end mill and use the cross slide to mill the slots.
Maybe drill out the slot first and use the end mill for squaring up the slot ?

Since I'll have 24 blanks to play with I'd like to have a milling attachment. I was thinking along the same lines as
Ryobiguy but mounting the vice directly to the toolholder.

Frank Ford
10-22-2006, 10:48 AM
Before I bought my first table top mill, I got one of these:

http://www.use-enco.com/ProductImages/7919356-11.jpg

It wasn't all that expensive, so if you want to try milling on the lathe I suggest you consider it before you tear up something important with or on your lathe. I've used it only for light duty stuff, and just as the others have said, the lack of rigidity is serious issue even with this dedicated accessory .

IOWOLF
10-22-2006, 11:00 AM
I used a Palmgren also ,still have it, Haven't used it in 10 years.

I done graduated from asking for trouble.

barts
10-22-2006, 12:00 PM
If you _have_ to do this, I'd pull the vise from the tool holder, remove the
tool holder from the compound and rotate vise 90 degrees. Clamp the
part in the vise and use a bolt in the t-slot of the compound (plus a
plate if needed to support the vise directly on the compound).

I would not use the setup shown.

- Bart

<edited for spelling>

Chuck U&R
10-24-2006, 06:33 AM
Thanx for the advice.
It's going to be a while before I can afford a real mill.
In the mean time I'll take your advice, go slow and hopefully I won't break anything.

JCHannum
10-24-2006, 07:04 AM
As mentioned in my previous post, many of what have become considered milling operations can be done in the lathe by holding the work in the chuck, particularly the four jaw or on a faceplate, and performing facing operations.

It is not until a feature like a slot or keyway is needed that the milling function is necessary. If you are simply facing a surface, the lathe will work just as well, and in many cases, much better.