[Jamf2]

How do you hold down your parts? Do you use a vacuum or build indiviuals jigs for each part? Has anyone made a tool changer for their router? Or used more than one router on their cnc?

[HuFlungDung]

I dunno, I just undo my belt, and they fall down and stay down, no problem. Now, where did I put my glasses?

[buscht]

How do you hold down your parts?
Do you use a vacuum or build indiviuals jigs for each part?

I do repetitive milling so I build jigs for families of parts.

Has anyone made a tool changer for their router?

I haven't, but here is a useful link.
http://home.insightbb.com/~joevicar3/default.htm

Or used more than one router on their cnc?

I use two routers on my CNC, one has a 1/4" bit for roughing and the other has a 1/8" ball nose bit for finish milling.

[CNCRob]

I do repetitive milling so I build jigs for families of parts.




I haven't, but here is a useful link.
http://home.insightbb.com/~joevicar3/default.htm



I use two routers on my CNC, one has a 1/4" bit for roughing and the other has a 1/8" ball nose bit for finish milling.

Hey buscht, sounds like you have a pretty neat setup. Do you have a photo of it.

[JavaDog]

I haven't, but here is a useful link.
http://home.insightbb.com/~joevicar3/default.htm

That is freaking awesome!!

[damae]

A cool trick I learned recently that does away with t-slots and clamps, vacuums and magnets:

double-sided tape.

It's very low-tech but it works fantastic! The parts come off with a little prying in the right direction. But during machining the tape is rock solid. A lot of machinists operating full size Vertical Machining Centers aparently like this trick too.

One caution - don't use the thick foamy tape. The stuff I have is about .008" thick, looks like normal clear tape, but sticky on both sides.

Another nice benefit is that you don't have to watch out for your clamps, in case the spindle crashes into them.

[JavaDog]

double-sided tape

Short of having to scrub all your parts with Goo-Gone, how to you ger rid of the residue from the tape? Both on your parts and worksurface?

[carlnpa]

I have been using the double sided tape to hold plastic parts. The residue is usually minor but does need to be addressed. I wouldn't leave the parts stuck to the table overnight as the residue might not be minor anymore. The goo goes away with vinly gloves and toluene.
I experimented with a vacuum table but kept getting part movement. Vacuum is good for sheets but as the parts get smaller, like 4"x5", very high vacuum with high volume is required, like -10-14.7 psi. The goo goes away with vinyl gloves and toluene. If anybody has an effective alternate I'd like to hear it.

[spalm]

I have used double sticky tape for years in the wood shop for holding all kinds of things during both turning and sanding. Use the type designed to hold down carpets, not the clear stuff. It does not really leave much of a residue (the clear stuff will). Don’t leave it on overnight. Pry the parts apart with a putty knife.

One problem I found with the CNC is cutting through it into the sacrificial board. This is a bit messy for both the board and the bits. Tape the parts so the router will miss it (or clean up afterwords).

Ronson Lighter Fluid is the cheapest, easiest, cleanest way to remove sticky residue. Works on tape, stickers, Band-Aids, and chewing gum.

Steve

[Geof]

...Vacuum is good for sheets but as the parts get smaller, like 4"x5", very high vacuum with high volume is required, like -10-14.7 psi....

It is actually quite simple: you strengthen your walls and windows and install an airlock for a door. Run the pressure inside your workshop up to 3 atmospheres absolute and vent your vacuum pump outside your workshop. This will give you a pressure differential across your vacuum table of about 40 psi quite easily. If you still need more holding power just run the pressure up and consult the US Navy dive tables to see how long you should spend decompressing in your airlock.

[JavaDog]

It is actually quite simple: you strengthen your walls and windows and install an airlock for a door. Run the pressure inside your workshop up to 3 atmospheres absolute and vent your vacuum pump outside your workshop. This will give you a pressure differential across your vacuum table of about 40 psi quite easily. If you still need more holding power just run the pressure up and consult the US Navy dive tables to see how long you should spend decompressing in your airlock.

Well, that is all well and good - but what about us people that live 150ft under the ocean already you insensitive sod!!



Thanks for the info re: the sticky tape, I'll file that one away...

[carlnpa]

Geof - You know your idea really isn't all that crazy, just scale it down. If you could pressurize one work piece surface you wouldn't need the vacuum, the pressure limit becomes part deformation/extruding. Unfortunately the forces on your container will be pretty high.

[buscht]

I'll try and post a picture of my setup.

In the meantime, here's an interesting link to a heat activated adhesive compound.
http://www.jlindustrial.com/catalog/...id=MTB-10240J#

It looks like its designed for milling applications.
Trent

[skippy]

"Run the pressure inside your workshop up to 3 atmospheres absolute"

Certainly dusting off your parts with an air hose and nozzle would become a thing of the past. So would sweeping out the workshop for that matter. You'd just pull the plug and cover your ears!

[damae]

Short of having to scrub all your parts with Goo-Gone, how to you ger rid of the residue from the tape? Both on your parts and worksurface?

Rubbing alcohol!

My machinist friend has been doing it that way for a while and it works great. The only catch is if you're machining a plastic that can be attacked by alcohol.

Edit: Just another note -- the sticky tape I'm using doesn't usually leave any residue. Right now I'm cutting mostly plastic.

I agree you shouldn't let it sit that way for too many days though.

[Jamf2]

Acetone and Toluene work really well also.

[Geof]

Geof - You know your idea really isn't all that crazy, just scale it down.

A very astute fellow.

My post was not entirely serious, perhaps people clued in to that? but on an individual machine basis it might work. If the machine was designed and built to work inside a pressure chamber it could be practical. Handling 4' x 8' sheets on a big machine may not be feasible but possibly the time saved in faster machining by having 'enhanced vacuum' clamping on a small machine would more than compensate for the cost of the pressure chamber and working on smaller sheets. You need to find a hospital that is being demolished and pick up a hyperbaric chamber for scrap value.

[One of Many]

How do you hold down your parts? Do you use a vacuum or build individual jigs for each part?

Use whatever is convenient for the task to fit what you have on hand.

We use MDF board, but also have a lot of surface area to pull vacuum through. And it takes a pretty good size pump to pull enough volume to maintain enough vaucuum on smaller surface areas. the Smaller machines won't have as many options for work holding.

Vacuum is the most common for sheet. A few ways to prevent leakage. One is to always leave material at the bottom of your cut and knife the part out later. This also works very well to hold small parts in place. The thin bottom is normally in the deburred edge area anyways. If you do break through, then have some duct tape or pieces of thin plastic like garbage bags at the ready to place over the leak.

If the part is of odd shape. Bondo or mill out a nest to have the parts captured in for a solid fixture on the cheap. This becomes a make do effort as required, but if at all possible, have the machine cut it out for a ready reference when performing secondary operations. Otherwise the part and fixture itself will need to be oriented, which may be unavoidable in many cases. Just keep in mind where making short work in looking ahead a few steps can have the task done with less chances for nesting error.

Has anyone made a tool changer for their router? Or used more than one router on their cnc?

A wine rack tool changer is by far the least complicated tool changer. Rotary carrousels are nice, but can be pretty high maintenance etc. Both will require some macro programming, but doing a pick-n-place in a line with the table already referenced is a lot simpler than creating and indexing another axis, but not impossible.

DC

[NardisAmps]

They make a double sided tape, that is for temporary situations like this, thats EXTREMELY adherent, and leaves NO RESIDUE (designed)! For purposes just like these! I been using it and it is truly great! Its not the cheapest but worth EVERY PENNY. It comes in several thicknesses also. I think I have a 2.5" roll and a 1" roll of it. I forget who makes it but I've been getting mine from Kurt, the Rep. for Debece in Nashville, TN (http://www.debece.net) Give him a call.

[HansM]

I only cut wood and I use 2-sided tape especially when cutting thin stock (with a sacrificial board underneath). I have not had residue problems with this one:

2-sided tape

this one is not clear it is about like masking tape. If the stock is long enough to reach the edge of the table I'll put a clamp there and use the 2-sided tape on the other end of the stock where the spindle is active and a clamp would be in the way.

Lance