Holding long stock and then the part for machining

I am designing a part that is about 1.5 wide, .5 thick, and 12" long and considering methods for holding which may influence the design.

The part is essentially a torque arm and has a round bolt pattern on one end and tapering to a narrower "handle" on the other. There will be lightening web features on each side. Think aircraft part looking light weight aluminum wrench. My vise is a 4" wide Kurt on my CNC machine so that won't help much.

I could use an aluminum fixture plate clamped to the table or in the vise. I can also design in a few lightening holes and use them as fixture fastening holes.

So I am looking for some trick techniques for holding stock and the flip of parts like this.

laminar-flow said:

I could use an aluminum fixture plate clamped to the table or in the vise. I can also design in a few lightening holes and use them as fixture fastening holes.

Click to expand...

Either of those two ideas are my thinking.

OK fixture plate. How would you hold the bar stock and then hold it on the flip?

One way would be to use little clamps to hold the bar, machine the face, then the pockets, then some features with threads. Then flip and attach using the threaded holes and align on a few features and finish the sides and the top. But then you would have to flip over to de-burr the 1st side perimeter. This would require a lot of threaded holes to hold it, then how do you clean up the threaded fixture holes to make them into features that look OK?

Post a pic or drawing of what you are trying to do..

From what you are saying, start with 3/4" thick stock. Grab in vise, machine... Flip into soft jaws, machine off remaining stock
and add any features you need...

KISS principal... I've screwed myself several(many) times trying to make a better mouse trap.. If you can grab it in a vise,
grab it in a vise.

Edit: single 4" vise... Get more vises.. I've got a set of soft jaws floating around here from back in the day when I had one
vise on one POS machine and another vise on another POS machine, They are about 20" long and where used on a single vise..
C-clamps on the outboard ends..

Yes, that would be fine if I had an 8" vise or another 4". I use that method all the time.

I am now looking at Mitee-Bite as they might have a solution. The design i am working on has some margin that might let me have a simple machined part.

Crocodile clamps every one should have a set in their box throw your vises out,who needs them

Bobw said:

Post a pic or drawing of what you are trying to do..

From what you are saying, start with 3/4" thick stock. Grab in vise, machine... Flip into soft jaws, machine off remaining stock
and add any features you need...

KISS principal... I've screwed myself several(many) times trying to make a better mouse trap.. If you can grab it in a vise,
grab it in a vise.

Edit: single 4" vise... Get more vises.. I've got a set of soft jaws floating around here from back in the day when I had one
vise on one POS machine and another vise on another POS machine, They are about 20" long and where used on a single vise..
C-clamps on the outboard ends..

Click to expand...

I agree 100%. Some guys like to build a damn fixture for everything. Anytime you can use a vise, use it. I also second the use of extended jaws and c clamps. A great time saver over building a fixture plate and clamps, plus buying mitee-bite clamps, etc. Now, if it is high volume and you can fixture multiple parts, that puts it in the "depends" category.

onecut said:

Crocodile clamps every one should have a set in their box throw your vises out,who needs them

Click to expand...

What the hell are crocodile clamps??

I am guessing that the link below are an example of "Crocodile Clamps"?

J.W. Winco, Inc. crocodile clamps are infinitely adjustable

I never heard of them before...

Not exactly those those appear to be just an adjustable height clamp.Dont have any photos,be honest thought you would know what I meant.You can make your own I did made 4 so I rarely use the vise or vises 12ins long easy 4ft long easy.They basicaly are made out a block any size mine are about3ins longx2x2,Drill a clearance hole thro block(2ins face up) to take a 5/8bolt about .750ins from end.Split them in 2diagnally so you have a wedge effect.Bottom half on the bottom cut a tenton to fit your table slot,on the angled face of bottom cut a tongue say 3/4insx1/8dp central Thats the bottom bit done.The top elongate the hole into a slot towards the back of clamp say 1.5ins long,now on the top diagonal cut a shallow slot say ,3/4wide + so its a sliding fit on the tongue in bottom.So thats it you drill clearance hole from top to bottom thro clamp-Your bolt goes thro this to hold clamp to table and drive the clamp forward.Split the block from corner to corner .This gives the wedge shape.Cut the tenon to fit your table slot on flat part of bottom piece .This is to get the drive forward(just like a vise but you can put them in your box and move them where you want them)Same piece but on angled face cut a tongue about 3/4widex1/8dp central.Thats the bottom half completed.On top half elongate hole towards back clamp to about 1.5ins long,So its now a slot.On angled face cut a slot 3/4x1/8dp make it a sliding fit to go on bottom tongue.Thats the clamp completed.I made 4 in case you have long jobs.Theres more you need some back slot blocks.Thes are easy made and take no time.Make 4.Get some steel anysize to suit whatever size you make your clamps,mine are about3insx2ins(2ins faces up) make them out of one piece and saw them into four when completed and skim ends just for show.So your bar say 8ins long.Cut a tenton on to fit your table slot along the full length I have mine offset not central.Drill a hole thro and c/bore the top to take a cap screw.This will be in 4 places as theres going to be 4blocks when you saw them up.So thats the back blocks done appart from sawing them into 4.So you now have 4 blocks that you put into your back table slots via the tenon you cut on bottom nip them down with your capnuts.Put your job on table or parallels,thers ways and means to do this but you will work it out for yourself its commonsense.Put your clamps probably will need some scrap packing and clamp your job.I have been using these for all size jobs for over 40yrs.Yes it will take you a few hrs to make the clamps not long for blocks.But no more humping 3/4vises on or indeed buying them.Getting long heavy jobs on off is easier getting jobs flat and parrallel is easier.Multi loads easy as you can see whats going on and have easy access to get a feeler guage under.As for a piddly little job 12x.5 no problem.Once you have made them you have them for life.Cost very little.Yes I sometimes use a vise but very rarely,normally a rough jaw for castings

Mike, yes, I am thinking on long jaws, but just looking around for other ideas. I do like fixtures though. This might not end up being just a few parts so yes, it depends.

How about an image of the croc clamps?

I will try and take a photo but I m not much good on this download stuff.How about an image or sketch of your job

The model is not finished. Since it is my design I am designing around available material and the ideas on holding and fixturing. Imagine that.

Steel parts are often economical due to the lower cost of the metal, but sometimes are more expensive than aluminum because of additional time required to machine them. Comparing to aluminum, steel parts are typically stronger. The common metal comes in numerous alloys with a wide variety of properties and is one of the least expensive metals. Steel is easily formed to make enclosures and other shapes and can be hardened, is magnetic and has many alloys that are easily machined.

I do parts like you are describing all the time... doing one right now. I almost always do op one in a vise (or vises depending on the length) and do op2 in a soft jaw (or pair). You can do it in a fixture plate, but it will drastically add to your time, since you need to build the fixture. If you absolutely must use a fixture plate, try and design in two dowel pin holes for indexing op 2 and either two tapped holes or two counter bored holes on the op1 side. Then use those to fixture Op2.

You would have less into two 6" Chinese clone Kurt vises than you would have into your fixture plate... unless your time is free.

Just thinking we do a lot of similar jobs but ally,but you cant hang about as its piece work the more you do the more you get paid and the times are tight.These jobs are ally foot long same thickness as your half inch.Only difference is its .500/.502.A lot of the lads either put a single vise on with long parrallels then a "G" clamp each end,Others have 2vises on.What a faff on stick them up against the back stop block direct on table,put a half ins key behind job at back same at front this is so you can put a face mill in without fouling the back block/or front clamp,M/c first side flip them over done with constant use of this method you will be able to tell if the job is down and theres no gaps by the feel when you tap it down of course you can use a feeler if you prefer