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?

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

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.

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.

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

That is freaking awesome!! Http://users.adelphia.net/~javamoose/Smilies/bling.gif

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.

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?

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.

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

...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.

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!!

:D

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

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.

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/product.jsp?origin=SEARCH%3AKEYWORD&id=MTB-10240J#

It looks like its designed for milling applications.
Trent

"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!

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.

Acetone and Toluene work really well also.

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.

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

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.

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 (http://www.tools-for-woodworking.com/index.asp?PageAction=VIEWPROD&ProdID=3862)

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

We use Mite-bite clamps from Kurt
They work very well, 1 part is a block of Aluminum 14x10x12
Holding on to the 12 in deep diamension in a .250 deep nest , 4 clamps then we rough mill the s!@# out of it. with a 2" shell mill 1.5 doc full diam. cuts at 50imp and it doses not move this is on a horizontal mill.
Brad

Tipex (typing correcting fluid) holds parts like cement and can b disolved off with acetone.

I also use Ultra Violet setting thick adhesive.

And, of course, double sided tape, vacuum and electrical tape (pretty stretchy).

For akward parts I machine an internal diameter jig to match the part that's to be held slightly smaller diameter and then stick it on top of the Lab heater for 1/2 hour, push the part into the jig and let it all cool down- hey presto solid grip.

Tipex (typing correcting fluid) holds parts like cement and can b disolved off with acetone.

I also use Ultra Violet setting thick adhesive.

And, of course, double sided tape, vacuum and electrical tape (pretty stretchy).

For akward parts I machine an internal diameter jig to match the part that's to be held slightly smaller diameter and then stick it on top of the Lab heater for 1/2 hour, push the part into the jig and let it all cool down- hey presto solid grip.


I haven't seen the typing correcting fluid ideal before. I'll have to try that.

Pressurizing the shop? That gives me an idea! I saw an auction at Boeing recently which included a couple autoclaves (24’ * 70’ and one smaller). They would give you all the negative atmospheric pressure you could handle, plenty of elbow room, while keeping you warm during these winter months (think of the increased drying time of glues & finishes!).

I've used 3M Super 77 spray adhesive (stipper butt glue) for odd ball flat aluminum parts. To remove the parts, I hit it with a torch. The glue fails at around 120-130 deg f. Clean up is done either with parts washer fluid, or brake parts cleaner.
Works well on sheet based parts featuring many many holes where vacuum just won't cut it.

OK pan people post what they have made, how it is connected to table and maybe a drawing. Currently i just cut key-ways in my table and use 1/4" bolts inverted and a plate ontop with a nut.

Thanks, Joe

I own a mill shop. We do strictly custom parts. Mostly raduis and i cannot have holes in parts etc. How hard is it to build a vacuum. So far all great ideas. But if im cutting a a 8' raduis piecs of oak 2" thick what would realy hold it down.

Has anyone ever cut 3/4 of the way down and cut the rest out with a router? I guess that is kinda of redundit but it would work.

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[/QUOTE]


Elaberate more on this please.

I own a mill shop. We do strictly custom parts. Mostly raduis and i cannot have holes in parts etc. How hard is it to build a vacuum. So far all great ideas. But if im cutting a a 8' raduis piecs of oak 2" thick what would realy hold it down.

The bigger the part, the better the vacuum works. I can say without a doubt that a vacuum will hold down 2" OAK. We do it all the time, cutting out 14 foot x 5 foot conference tables. You say you have a 8' radius, but don't say how big the part is. Long skinny parts sometimes have problems. If the part is at least 12" x 18" you won't have a problem.

Getting a good seal for the vacuum is sometimes an issue with solid hardwood. If your parts are warped or rough, you will need to make a gasket seal around the perimeter of the vacuum area.

Has anyone ever cut 3/4 of the way down and cut the rest out with a router? I guess that is kinda of redundit but it would work.

Yes actually, you cut almost all the way through, maybe leave .010". You can then trim with a bearing guided hand router, or run your parts through a wide belt sander and sand of the .010"

This way you can screw into the waste and not require a vacuum.
Or this works well with a vacuum and skinny parts that don't hold down well my themselves.

Has anyone ever cut 3/4 of the way down and cut the rest out with a router? I guess that is kinda of redundit but it would work.

Our router has a pod vacuum system, so we do this all the time, because we can't cut all the way through on smaller parts. Like trent says, use a straight bit with a bearing, and just leave 1/32 or so.

A wine rack tool changer is by far the least complicated tool changer. Rotary carousels 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


Elaberate more on this please.

A wine rack type (http://www.cncrouterstore.com/detail_info.php?num=5383) is in a straight line mounted on the table end. Some types make the pick up a simple task for the x,y to position over the selected tool then just z down to grip and lift. Others still use the finger holders that are common on rotary changers. They must slide the tool in and out of the station gripper with the x or y axis.

A rotary carousel (http://www.gspinc.com/products/routers/sabre-atc.html) adds another axis to control.

The sliding wear and tear on a rotary carousel becomes a consumable part when it will no longer hold the tool properly to pick it up, not to mention chucking it out while in rotation.

Hope that helps clarify the differences.

DC

I'm wondering if anyone has used these types of inserts for hold-downs on a router table. I was thinking of spacing these throughout the wood base table and using to hold down various shapes.

Any drawbacks?

John (Bloy)

I have not used the inserts you mentioned but I am thinking about using the inserts below soon.
http://www.mcmaster.com/param/asp/PSearch2.asp?reqTyp=parametric&act=psearch&FAM=insertsplasticwood&FT_104=4054&FT_137=31621&FT_147=60655&FT_158=10894&FT_357=10971&FT_1415=70866&FT_2603=113624&desc=Zinc%2DPlated+Steel+Self%2DLocking+Tee+Nut&sesnextrep=420921705284952&ScreenWidth=1024&McMMainWidth=817

I have not used the inserts you mentioned but I am thinking about using the inserts below soon.
http://www.mcmaster.com/param/asp/PSearch2.asp?reqTyp=parametric&act=psearch&FAM=insertsplasticwood&FT_104=4054&FT_137=31621&FT_147=60655&FT_158=10894&FT_357=10971&FT_1415=70866&FT_2603=113624&desc=Zinc%2DPlated+Steel+Self%2DLocking+Tee+Nut&sesnextrep=420921705284952&ScreenWidth=1024&McMMainWidth=817

I just ordered some of those from mcmaster a couple of weeks ago for a new table im getting ready to start.

John (Bloy);

There is a drawback to using those inserts and that is they sometimes unscrew when you are taking the bolt out. This is less likely if you make sure you use lubricant on the bolts.

If you are putting these inserts into MDF drill a pilot hole the root diameter of the outer thread and go in about 30% deeper than the length of the insert. Then counterbore about 1/16" to 3/32" deep to the crest diameter of the outer thread. Installing the inserts is easier using a length of rod with a stud in the end that fits the internal thread of the insert and a tee bar at the other end. Make the rod about 6 to 8 inches long so you can see that it is perpendicular to the surface and your insert is going in straight. These things are a real pain to put instraight just using a screwdriver.

Screw them down until the top is flush with the bottom of the counterbore for machine strength. I have tested the 1/4-20 version of these inserts in MDF and they will pull out at around 300 lbs straight pull.

DMGDESIGNS;

The backside inserts you reference are easier to insert than the other type and they are stronger but they have a big drawback. They are made of very soft steel and lubrication is essential. Even then they are prone to strip or sometimes they will gall up on the bolt and then break free from the mdf or wood and spin in the hole. If you cannot get at the back side to hold them with vise grips getting things apart can be a real pain.

I was wondering if someone could explain to me how Helical Inserts like item number 96246A755 at mcmaster.com works. Are they to repair a thread thats already there. If so; is one that has a internal thread size of 1/4-20 for a repair of a 1/4-20 thats already there. If it is how do you get it into the original one. Do you just tap it out to a bigger size? Thanks- Robbie

I used these on my 6x4 router.. so far they have been perfect and are easy to install as the taper helps align them to the hole..although screwing a few hundred into a laminated mdf tabletop isn't exactly fun..

They've been more than sufficient and even hold down 10mm aluminium for milling/routing without moving.

Got them from http://www.profhdwr.com/55008.htm

Robbie you have figured it out. It has been a while but you do get a special tap for the 1/4-20 helical and run it through the 1/4-20 hole. Then screw the insert in and break off the little tab. Now you have a repaired 1/4-20 hole.
I was wondering if someone could explain to me how Helical Inserts like item number 96246A755 at mcmaster.com works. Are they to repair a thread thats already there. If so; is one that has a internal thread size of 1/4-20 for a repair of a 1/4-20 thats already there. If it is how do you get it into the original one. Do you just tap it out to a bigger size? Thanks- Robbie

Thanks Mark

has anyone used toggle clamps, like these
Toggle Clamps (http://www.bosstoolsupply.com/index.asp?PageAction=VIEWCATS&Category=888)

automizer, I have used toggle clamps. You just have to be careful when programming to make sure you don't accidentally run into them during a rapid move.
It can be pretty ugly.

In the shop where I worked at they used double sided tape. Removal of the residue? A few small squirts of MEK (Methyl Ethyl Keytone).

Not the best idea as MEK is a known carcinogen but, hey it worked!

Greg

Not sure how widely it's available overseas, but in here in australia Eucalyptus Oil is used to remove labels/tape, almost anything leaving a sticky residue.

And it's natural! ;)

If you get the Double Sided tape from RS catalogue (the economy stuff) if just peels off in one go leaving virtualy no residue- I use this on plastic lenses and it holds the parts real good- I give the lenses a wipe with Methanol just in case they are slightly contaminated- i usualy use Acetone to remove residue, but not on plastic lenses obviously. The other expensive Double Sided tape is no good as it goes all gooey.

http://www.rockler.com/ecom7/product_details.cfm?&offerings_id=2349&SearchHandle=DADBDADBDADADDDGGBGFGBDHGDDGDBGECNGBDIDIGFCNDEGEDJDECNDJDIGDDFCNDHDDDBDAGDGCDJDGGFGCDIGEDADADADBDADADADADGHECAGOHFHEHDDADADADEDADADADADADADADBDFDADADADBDADADADADADADADADADADADADB

SPAENAUR. Try a search for them and then email them with the part numbers
191-020
191-021
191-001
They are a tnut with a rectangular flang on the bottom and holes for screws to keep them in place
The part number 191-001 is for 1/2" bolts.

http://images.rockler.com/tech/68387.pdf

Hi Guys

I have been usin g2way tape for years also. I have found a tape that looks like masking tape but sticky on both sides where the middle layer is paper. Same company has tape with a mylar center while stronger, I have not has the best results when trying to remove it.

the majority of the parts I machine are aluminum or plastic (http://tinyurl.com/6t2oa)
I have a nice hot plate that I use to warm up the base plate. I have never measured the temperature, but just at the right moment, you can turn off the heat and very easily remove the parts and the tape with no leftover residue.......But go a little over the correct temperature and you ahve a big sticky mess as the adhesive releases from the paper. On the mylar stuff, the adhesive seems to always come off the mylar no matter what.

I have 6 parts stuck down with the tape right now running in the machining center! If it werent for 2way tape and superglue Id never get anything done!

Oh, i forgot to mention that I also use the hydraulic press to seat the material to the base plate. I find that when both surfaces are very flat and the press is used I can use flood coolant but if I use extruded bar stock, the surfaces is not flat or smooth enough and the coolant will migrate under the parts and they will release...

The tape I use comes from Related Products 800-423-3564 The sales guy I buy from is Jim Leiberman. He always gives me fantastic service even though were a low volume user. I but it in several widths up to 6" wide.

Here is a link to a vacuum fixture I made for machining cred card stock http://tinyurl.com/coave


Hope this helps someone

Bill Griffin

Sorry Guys, My previous post was in response to the thread "Holding down your parts " Sorry I didnt copy the original post in the maessage.

Regards

Bill Griffin

One of the first projects I did on my mill was to make Mitee-Bite type clamps, since I didn't want to pay $40/per or whatever they are. Just a hex nut milled and a cavity with an eccentric bolt in the center. They are great! I'm sure the real ones are even greater still. Real handy.

can you post a picture of your clamps?

By request, here's a picture of my clamps. I'm not exactly going to apologize, but realize that I had a new milling machine, and it was, "Hmm what can I make?", and my lathe was not what it is now, either. A little rough, is what I'm saying, but they do the job. The eccentrics are turned on center, then drilled OFF center, and the bolts brazed into the hole - hex nuts are milled and flat and a cavity made with ball mill - could be turned, too. I have a sine plate with 1/4-20, so the small ones are for that, same with the screw clamps, also just brazed together. Threw in a vise clamp, too - simple project that's great to have.

I use double sided tape a lot; Denatured alcohol will help you remove your parts easily and without residue.
Permacel makes our tape, it is paper based.
I work mostly with plastics.

I have been looking for double sided tape and can't find it anywhere? Does anyone have any suggestions?

At the last school I taught at they had a real simple vaccum system. They had a venture valve, although a shop vac works too sucking air from a 3/8" or so hole in the table. They would then make small thing (1/4") pieces of wood with a hole in the center that would line up with the suction hole in the table. On the top of the small piece of wood they would run foam rubber around the edge. Place you work peice on top, turn on the vacumm and the work peice would suck right down. Very strong. They made one for their router station as well that ran from a shop vac.

The double sided tape I use is the stuff intended for carpet. You can get it at the Depot in various widths. Just go to the carpet section. I find that most of the residue just rubs off with finger pressure if you remove it with in a day or two. Rosonol (or ‘Ronson’) brand lighter fluid is a great solvent for any sticky you may find troublesome. It can be bought at any grocery store. It also works for chewing gum and other labels that may be stuck to stuff you buy.

Steve

I've used them extensively when I was doing dicast parts, but mostly for drilling.

You have to design your fixture so that the clamping arm isn't the thing the machine is trying to throw accros the room, as the machine will generally win!