[ozzie34231]

Sometimes setup is the most difficult/interesting part of a job, especially CNC.
Can someone give me their idea on the best way to setup an indexing head on a milling machine table at a specific angle to the X axis.
The head is a C-5 collet fixture with 360 rotary settings. I want to set its longitudinal axis at an angle with the X axis of my machine.
I'd like it to be rather accurate because I'm making a carbide insert cutting tool.
I have an idea or two, but I'd like to see what all of you come up with.

Thanks,
Jerry

[Mcgyver]

ahh a puzzle...but first, an angle to the x axis is a cone - what direct you want to angle it – in a plane with the y axis or z axis? Ie tilting the dividing head or bolting it to the table at an angle?.

First the low tech minimal tooling idea (I guess only for small angles at angle in the xy plane) put a 1" piece of drill rod in the dividing head and an indicator in the spindle. By moving the quill, take a reference reading near the head, the move the table along the x axis a set amount and measure again. Pythagorean theory and trial and error tapping with brass hammer get you there.

To be more precise, we dust off the sine bar and gauge blocks. If its xz, just gauge block, sine bar and parallels in contact with a piece of drill rod in the head. If its xy, Clamp a largish tooling block to the table and indicate it to the x axis. Then gauge blocks, sine bar, against the block and drill rod in the head, by bringing them into contact you are at the right angle.

If you don’t have gauge blocks and sine bar, you can do an accurate job of making them. Use Pythagorean theory, all you really need as two round bars held a constant distance apart and instead of actual gauge blocks just machine a piece the required height of the stack. Maybe a PITA, but you wanted accuracy

So what super easy way did I miss??

[Kmed]

ANother way is to get it to the rough angle then use a dial indicator over say 1" the calculate the the angle by using the indicators reading. I dont know how you want the angle, but you can use this page to figure it out using a little trig.



Right triangle trig

[ozzie34231]

Okay, I should have said in the xy plane. My best idea was to get close with a protractor to the table edge and then refine with a 1/2" or 3/4" bar about 3" long in the collet and two computed locations along the line, 0,0 and the computed coordinate.then a wiggler or my laser edgefinder.

A sine bar on edge would be a good idea too.

Any other ideas?

Jerry

[lerman]

Okay, I should have said in the xy plane. My best idea was to get close with a protractor to the table edge and then refine with a 1/2" or 3/4" bar about 3" long in the collet and two computed locations along the line, 0,0 and the computed coordinate.then a wiggler or my laser edgefinder.

A sine bar on edge would be a good idea too.

Any other ideas?

Jerry

Since we have a CNC machine, clamp a piece of scrap plate to the table. The drill/ream some holes for dowels at the proper angle and a useful distance. Put a straight bar against the dowels for alignment.

The precision is as good as your mill.

Ken

[ozzie34231]

Excellent!

[Mcgyver]

I think Ken takes the prize!

[Geof]

Just to horrify the purists! In the next month or so I will be drilling a pattern of alignment holes directly in the machine table to simplify setups.

[Ken_Shea]

Geof,

Can we see pictures

[Geof]

Geof,

Can we see pictures

Yes, just give me until the end of September.

[miljnor]

well its a hobby machine and I have bought used machines with dimples in the table. But I make it a point to fire anyone who drills into my milling tables. While your doing it intentionaly most of the time its a careless accident, and I can do without careless accidents into my 30k to 150k machine tools.

Just out of curiousity is this a purpose build machine? becuase you can't take those holes back! ahhhhhhhhh the horror of it!

[ozzie34231]

Thanks to all,
During the night I was thinking about this and the pegs seem the perfect answer. Actually I only need one hole, the other peg can be held in the machine spindle. That way if I ever want to set up for a similar job, even a different angle, no problem.

Jerry

[ozzie34231]

Hmmm, more thinking,
I don't need any holes. If I turn a peg with a large base, say a 3/8" with 1" base, put the peg in a tool holder snug but not tight, lower it to the table, clamp the peg in place, zero the machine, move off at the correct angle, and inset another 3/8" peg, then I have it. setup time a minute or two after the peg is made.

Jerry

[lerman]

Some more thoughts.

On the back edge of the table of my mill, I've bolted a piece of steel that sticks up about 1/2 inch. That is used as a reference edge for many of my setups. (I rarely have jobs that require overhanging the back of the table.)

So, if I were doing this job, I'd machine a suitable triangular piece that I could place against the reference edge that would provide a new reference at the proper angle. (This assumes that I would need this setup many times.)

Then setup consists of putting my reference triangle on the table and pushing my index fixture against it.

That would be as close to zero time as you could get.

Ken

[Geof]

well its a hobby machine and I have bought used machines with dimples in the table. But I make it a point to fire anyone who drills into my milling tables. While your doing it intentionaly most of the time its a careless accident, and I can do without careless accidents into my 30k to 150k machine tools.

Just out of curiousity is this a purpose build machine? becuase you can't take those holes back! ahhhhhhhhh the horror of it!

Just so nobody has a heart attack. It is a standard off-the-shelf machine (some shelf!) and the manufacturer provides it with a blank table so the user can drill and tap holes in appropriate locations for fixturing. They do instruct not to drill all the way through the table.

[ozzie34231]

Good thought Ken. Unfortunately this is an inexpensive device, I think its called a spin index, and I doubt that the casting at the base is aligned with the axis. so I really need to setup using something held in the collet.
The pin idea really sounds good to me. The pin would need to stick up about 2" plus, but if I have any doubt about the accuracy, once I'm that close I can indicate along the test piece, running along the angle with CNC.
Thanks for your thoughts, I'm always happy to hear a new trick.

Jerry

[DieGuy]

Just to horrify the purists! In the next month or so I will be drilling a pattern of alignment holes directly in the machine table to simplify setups.

OMFG!

That is what fixturing is for! (nuts)

[gripper]

on all of our mills we have fixed a 1" thick plate (using t-bolts) to cover all of the bed, that way it avoids all the little mishaps and you can use it for fixturing and in the end you still have a nice bed when you come to sell your machine. Looks professional.

[Geof]

on all of our mills we have fixed a 1" thick plate (using t-bolts) to cover all of the bed, that way it avoids all the little mishaps and you can use it for fixturing and in the end you still have a nice bed when you come to sell your machine. Looks professional.

Yup, I do that on some of my machines. I have found that the nice bed did not get maintained because of galvanic corrosion between the attached plate and the cast iron table. This has occurred with aluminium plates, steel plates and ductile iron vise bodies, with or without a film of oil or grease.

I did not expect to create such consternation but considering the machine comes with a blank table; no tee slots, no holes and non-magnetic my only other option is doubled sided tape.

[Mcgyver]

make sure you use the kind that leaves no sticky residue