Vise Setups For Milling Multiple Parts

[JHoi]

Hello,

I have a project coming up that will require me to square up and drill a bunch of the same part. Anywhere between 6 and 12 dozen at a time. I typically do one offs or small runs of things messing about. This is crossing over into more of a production mindset for me and I want to approach it as such.

The part is basically a 2"x4" piece of .187" thick 6061 aluminum with a centerline hole on both ends. The 2" dimension and the thickness are not toleranced tightly, so I figured I would use 2" flat bar to start. I can either bandsaw or chop saw the stock to say 4 1/8" pretty comfortably.

From here I want to clean up the ends and then bring the length into spec....I have a mill drill and a Kurt 6" vise clone. I have a basic fixturing clamp kit as well as parallels, 123 blocks, and a vise stop. How would you go about setting up the parts?

If I laid them in the vise on the long axis I could even them up and hit them with a big endmill...then flip them back over tight against a stop since that side would be square now and then endmill them into spec. Would you stack them on the .187 dim with a piece of paper or stack them across on the 2" dimension? I was thinking of going the .187 dim since that would leave the vise in contact with each part.

Or I was thinking I could even them up, clamp them and then stand them up on the long axis with piece of paper in the vise to take out the slop. Then I could hit them with a fly cutter or a face mill...once they are evened up flip and then bring them down to spec.

Any pros/cons you can think of with either or another route entirely? How many would you try to do at a time?

JH

 

[Paul in OKC]

A mill drill being one of the round column machines? I had one once and did a lot of work on it. 4" is a bit to be standing up. Might try doing two or three at a time clamping on the 2" width. Not sure if a big long endmill would do well in that machine, but might. Do all one end, then set for length and do the other. I would then set up to drill. Should be able to drill both holes in one set up, unless I am missing something. Once the parts are to length and close to the same, you should be able to drill one hole, then flip and drill the other. HTH

I guess you could true up one end, then stand them up and C clamp a bunch together and hold in vise on the 2" width. I did some parts like that once and it worked well.

 

[Jimsehr]

If you are going to do production runs I would look into going to a production saw shop. Some of the new saws can hold very close sizes and are very fast. Much faster and cheaper than doing it on a mill.
jimsehr

Parts should be finished to print by the saw.

 

[T Bredehoft]

If you are going to do production runs I would look into going to a production saw shop. Some of the new saws can hold very close sizes and are very fast. Much faster and cheaper than doing it on a mill.
jimsehr

Parts should be finished to print by the saw.

Or....start with material the thickness you want. When you saw it you will be loosing a large percentage of your stock. If you finish at 3/16, you may loose more than 1/8 sawing and milling. Loosing both time and material is costly. Don't try to gang mill the end, either, there's no good way to hold them. Mill one end on all pieces then the other end on all pieces.

CNC with a narrow vise (less than the length of the piece) could finish both ends and drill your holes all at one clamping.

 

[rallycat]

For 6 or a dozen parts cut them yourself, for 6 dozen have them cut to size. It is worth the expense.

If you are going to do production runs I would look into going to a production saw shop. Some of the new saws can hold very close sizes and are very fast. Much faster and cheaper than doing it on a mill.
jimsehr

Parts should be finished to print by the saw.

If you use flat bar stock be careful about clamping across the 2" width. There is enough variation that some pieces will not be clamped tight, either getting pushed to one side or pulling up. If you slide the stack over so there's an inch sticking out of the vise you can clamp the stack with a couple small machinist clamps to keep it secure.

If you set the pieces in vertically use a block or angle plate to back up the stack in the vise and clamp across the top - this will prevent chatter.

Drilling will be quick, just set up your stop and parallels so chips won't get trapped between the part and vise jaws. If you will be making these parts in the future, think about making a drill jig that could hold half a dozen at once for the drill op and use a drill press.

 

[JimDawson]

I would check with Coast Aluminum for getting them production cut. They are the guys I use for production aluminum parts. They have high speed, and very accurate CNC saws. If you buy a couple hundred pounds at a time their prices are very competitive.

Then I would set up in the mill with stops at both drill locations, lay a stack of parts in the vice, put a clamp on one or both ends as needed. Drill the holes. As rallycat suggests, a drill fixture would be a good plan for ongoing production. It's perfectly acceptable to bid a setup charge into the job or as a one time separate charge.

 

[JHoi]

Thanks for all the replies guys.

For these smaller runs I'm planning on doing them in house...if it breaks into large qtys then i will outsource them. Saw house is a good idea I hadn't thought of. Pretty sure they wouldn't want to mess with less than 500 or 1000 pcs of these. I thought about waterjet too...but plate is so expensive compared to flat bar that I bet the cnc saw pricing will be way better.

In this case it gives me an excuse to buy a few more tools (who can resist that) and the wife can't even complain since they will be paid for Its also about going through the thought process and turning that into some parts.

I'm thinking along Paul's lines here....It is a round column mill...one size below a proper knee mill. If I can do 5 or 6 at a time I'll be a happy camper. Square up an end...flip and do the other end. I'm also planning to use a corner rounding end mill for the first time to put a proper small radius on the edges.

As far as the drilling goes I was thinking of clamping in the mill against a stop and then flipping. I think that would give better results then trying to tram back and forth between the holes and it will probably be faster. Holes will be 1/4"...I want them to be placed accurately but they don't require reamer precision sizing or anything. What guidelines do you go by for deciding when to use a centering bit or not. I'm also looking at maybe some of the stubby or jobber length bits...but that limits how many I could drill in a stack so......

Drill press jig is something I should probably play with though. How would you go about building one...mdf and a couple pieces of wood clamped to the table? Toggle clamps for hold downs? Sometimes I wish I could spend a month in a cabinet shop...wood working guys seem to be the fixture masters of the universe.

 

[JimDawson]

Water jet would be crazy expensive, so would laser cutting in aluminum. They would be happy to saw one bar into lengths (58 or 59 pieces in this case depending on saw kerf)

Toggle clamps would work very well for the drilling operation, not for milling. A 135 degree split point won't walk as much as a standard 118 degree drill bit.

For a fixture, I would use a 1/2 inch aluminum backer, and some dowel pins as locaters. Be sure to counterbore the dowel pin holes a bit so you don't get chips hung up in that area and screw up your positioning. Be sure to think about chip clearance. Spacing the plate off of the table is a good idea.

 

[Bill C.]

You could use a "T" plate dedicated to this type of part. You would clamp your stock flat to the surface of the plate and use finger clamps to hold the stock in place. When I worked in Texas some of the guys used them. Basically two pieces of aluminum stock bolted together. I think about 3/4" to 1" thick. The surface had several tapped holes to bolt the clamps where needed. Just a thought.

Good luck with your project.

I couldn't find a simple example of what I was referring to, Sorry

 

[Paul in OKC]

As for a centering bit, what size is the hole you will be drilling? The shorter screw machine length drills are good for drilling without a center drill first, again depending on size. If 1/4" or up, they will do great, just start with lightly 'tapping' the drill bit (while running) on the material the drill on through.