Workholding Tape

[crazy^millman]

Another thing I have done is hot glue it down. Most time a good pop wit ha dead blow and the parts will release. Might get that .25 doubled disked like suggested and now it is just a matter of doing the detail work. You could also picture frame it. Leaving enough stock around the outside to hold it down and put dowel pin locations. Then machine everything locate on the pins and then finish using support underneath.

 

HTH

[rhettmandel]

I use permacel double back tape. Its comes in precision thickness. I mainly use .005 thick. I works great for aluminum and plastic. I even used it for milling titanium. I like it because it comes off easy with alcohol, and the adhesive is like masking tape so it is very clean.

 

Heres a link

http://www.findtape.com/shop/product.aspx?...1280&height=862

[Dave.L]

quote:

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Wow, that's quite a ratio of start to finish removal! I guess it depends on the condition of the metal, but do you foresee it curling up as you release some of the stress in it? I know we've had that problem before. How many times you going to flip it? Start with a vise, or clamps? I guess at a 1/4 the double stick tape might work, if it's flat enough to hold it.

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Our experiences have been it's best to start with plate compared to bar or sheet.

 

If we use 1/4 inch, we will estenically get our part from the center. Because, yes the stresses in the material are best removed by cutting top and bottom and equal amount. We may use 3/16 both nothing less. The key is the first cut. We will use a method that puts ZERO distortion holding force on the part. Once we have a very, very, flat surface to start with the rest is easy.

 

Thanks for all your help and suggestions

 

PS Rizzo, is 3M 665 the tape you were talking about as another mentioned?

[PaceToolmaker]

Ive made vacuum fixtures a few times for parts like these with good results or started with a bigger plate then mill the center down leaving tabs then cut the part and finally drop the tabs out.

[CNC-ERIC]

Hi,Dave,

 

we use 3M Scotch indor carpet tape CT1030, which is very strong double side tape.

 

Eric

[indyhonda]

Hi there first time poster here.

Ive used tape to hold down thick to thin materials for years. The maker is "intertape"

The part # at Mcmaster is 76405A15 for a 2" wide Roll. They have in that series 3/8 to 4 inch widths.

The only problem i have with it is you have to machine either dry, light mist, or with an occasional mist of w4-40. You cannot get this stuff wet with oils. Your part Will FLY! keep it dry and youll need a crane to lift it off.

I usually use brake clean, or alcohol to remove after im done. If you wait long enough it will float off without any prying.

Ive machined flatness/ parallelism within .01 microns or .0005" in aluminum. However id get the material stress relieved before id attempt going from .25 to .0625 or youll be fighting the taco effect as you make sucsessive cuts.

Good luck!

[Rob @ Target Machine]

Welcome to the forum.

 

 

I've been a long time user of 3M tape, but recently we have been using the intertape carpet tape.

 

I can get 45 minutes of hold time with moderate coolant. We use acetone to remove surface oils and we clamp the part/block in a vise for a while before running that part/block. If you turn the block to all 4 sides seating the part evenly, .0005 parallelism is a breeze.

 

I've had really nice results with stock right to size. Our stock is from Germany and has been stress releived by stretching.

 

BTW - Sheet stock has way less internal stresses than plate stock.

 

Flat w/in .005 or better over 5 inches after machining. (.001" per inch). Sometimes a little "tweak' is needed afterward.

 

As a rule, I try to avoid facing. A face mill puts too much stress into the material, an endmill will work much better if the thickness isn't good to go.

 

[Dave.L]

Well,

 

I ran these parts today. I purchased the 3M 444 tape Chris Rizzo recommended but I whipped out.

 

I designed a fixture using Mittee Bite pitbull clamps (I have used these many times). As a backup, I could have used the tape in the fixture pocket but did not need to.

 

Since I needed to have T651 temper, I had to make these parts from plate, .25 thick, final part thickness .063 +/- .005.

 

I took the final part right out of the center of the thickness for stress reasons.

 

First part is flat within .002".

 

I will run more reducing my clamp pressure and should probably get the flatness down to .001" or better, the spec is .005"

 

The tape has however come in very handly for holding parts for CMM inspection.

[Kevangel]

here ya go

[Chris Rizzo]

dam sorry Dave that didn't stick for ya! Suppose I should have asked, but I'd say that .250 plate down to .063 is a tall tape order. I generally don't hold material thicker that .125 with tape. Also the biggest tool I safely use is .1875.

[Dave.L]

Chris, it might have I just did not try it. That tape is very sticky.

[jeff]

We just ran an aluminum job and I bought that Permacel tape that was recommended by rhettmandel.

17" x 17" x .500 blanks, mill to .350 thick and hoggin out a bunch of pockets with a 1/2" Blizzard @200 IPM.

This tape is excellent!

And the best part is that the part comes off clean, the tape comes off clean! There is no glue residue to wipe off at all.

Way better than carpet tape that's for sure.

Just have to make sure the side down is FLAT, and we also wiped the part with acetone or denatured alcohol beforehand.

Thanks for the link

[Rocketmachinist]

How many of these tapes were you able to use coolant on? I am doing some stainless and would prefer to use coolant but if necessary can use a mist.

[jeff]

I used coolant on the Permacel, but I drilled the holes in my part last to be sure that it didn't get between the part and the tape.

[Chris Rizzo]

quote:

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I ran these parts today. I purchased the 3M 444 tape Chris Rizzo recommended but I whipped out. [Razz]

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Oh I read that as the part "whipped out" I'm now assuming you wimped out.

 

I really don't know how thick you can go with the 3m 444, I just use it for thin stuff. For all I know it could hold 3/4" plate.

[Dave.L]

quote:

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Oh I read that as the part "whipped out" I'm now assuming you wimped out.

---

Maybe some day I will learn how to spell

 

quote:

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I really don't know how thick you can go with the 3m 444, I just use it for thin stuff. For all I know it could hold 3/4" plate.

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Chris, I bet you could. I was just worried about slight movement and tolerance issues.

[MACHINEMASTERG]

im alittle late chimming in but we use 3M VHB (very high bond)this stuff is used here in assembley and we have been using it alot in the shop it holds great

[#Rekd™]

Clamping or put it into a press it after the tape is applied helps a lot in most cases. Acetone will help release most tapes.

[Newbeeee™]

FWIW, we do a lot of parts this size and thickness.

We use stock thickness mtl, oversize length + width and use strip clamps on a fixture.

Do the work and m/c the profile leaving a 2thou thick membrane and break them out.

Obviously hand deburr the back side.

[Bob W.]

I know this is an old thread but I was searching for info about Pitbull Clamps and I ran across it. I tape stuff down all the time and I use Shurtape available from Western Cutting Tool. I'm not sure who the manufacturer is but it is great stuff. The best way to clean the parts bar none is in the kitchen sink with warm water and dish soap. I have tried everything (acetone, Brake kleen, paint thinner, etc...) and nothing works as well as dish soap, not even close. Like vacuum work holding, the holding power is a function of surface area. I can start to take pretty healthy cuts on 1/4" thick stock once the taped surface area is greater than ~48 square inches. More than that and one can rip on much thicker material. High speed toolpaths are invaluable for machining taped and vacuum fixtured parts because the forces are kept pretty consistent. It is amazing what can be accomplished when taking light cuts with a small cutter using the high speed paths with very low cutting forces.

 

I use heat to release the tape and I have a dedicated skillet in my shop just for this purpose. If there is tape residue, the best method to remove is with paint thinner and there isn't a close second.

[Justin Beebe at Folsom Tool]

I just used tape to hold down some parts last week. Material was 7050 T6 Aluminum. Material size was 1.250 X 17.00 X 18.00. I used three strips of tape equally spaced and faced the parts with a 3.00 diameter facemill. It worked like a charm.

[Bob W.]

I just used tape to hold down some parts last week. Material was 7050 T6 Aluminum. Material size was 1.250 X 17.00 X 18.00. I used three strips of tape equally spaced and faced the parts with a 3.00 diameter facemill. It worked like a charm.

 

I avoid using a face mill with taped parts because if it does come loose it can generate some serious velocity. If I must use a face mill, which I have done, I will always set up the toolpath such that if the part does come un-stuck it will get tossed toward the back of the machine and not through the viewing screen. I take this same approach when facing vacuum chuck parts that haven't been pinned to the sub-plate. Never had an issue though, it just makes me nervous.