Vacuum Film Technique - A Quick Explanation

[Brady Watson]

Due to time constraints, I have not had the resources to get a proper ShopBot Web Column article properly done...So until I do, here's a quick & dirty write up of what I call the 'Vacuum Film Technique'

I have been using this technique for the past few years to hold tightly nested, small and/or thin parts securely to the vacuum table without the need for tabs or other labor intensive band aids. I have used it to machine all types of plastics, non-ferrous metals (silver nickel, brass, AL) and even thin wood veneer.

(pics to follow at some point...I'm not at the shop at the moment)

I'll explain the basic concept using a 4 X 8 X .1875" Cast Acrylic sheet as our material to cut. Let's say we have an entire sheet completely nested with parts with little or no scrap, in order to get this job we desperately need to keep afloat.

I'll start by cleaning one side of the acrylic paper with a dust brush. Then I will adhere two 24" wide strips of High Tack transfer tape, taking care to avoid bubbles. Use a J-roller to firmly adhere the tape to the paper on the acrylic sheet. Then I take 6" wide mounting tape, which is very aggressive & double sided, and stick it to the entire back of the transfer tape I just put on. Then I take a $7 4X8 sheet of Coroplast (corrugated plastic) and laminate it to the mounting tape to give me a layup that looks something like this:

Acrylic Layer
High Tack Transfer Tape Layer
DS Mounting Tape Layer
4mm Coroplast Layer

I run the J-roller over the whole deal and make sure everything is bonded really well. Then I place the whole layup right on my universal vacuum bleeder & pull vacuum. I cut my parts, keeping an eye on things to make sure I am not asking too much from this hold down system by cutting too aggressively. If I get part movement, I make adjustments, but it is rare that I have to do this. I cut all the way thru the acrylic, tapes and well into the coroplast. This allows me to cut all the way thru the parts without ever breaking vacuum. The vaccum holds the coroplast...the coroplast holds the tapes to the acrylic.

When cutting is complete, I simply peel off the acrylic along with it's protective paper. The super aggressive adhesive remains attached to the coroplast and the transfer tape easily peels off the paper backer on the acrylic without a hitch. The mounting & transfer tapes are so thin that adhesive build up does not typically present a problem.

That's it! Now you can cut parts you only dreamed of cutting before!

Everything I mention here is from HarborSales.net:

Mounting Tape
6" x 72 yd | White | Double Side Adhesive
216 Double Coated Poly Film Mounting Tape
Price: $64.77 ea

Transfer Tape
#4076 | Conform/RLA | Higher Tack
24" x 100 Yards
Price: $58.00 ea

OK - This needs to be said to many of you. You MUST charge for part fixtures since there is a consumable cost - the coroplast and tapes, plus your labor in laying everything up. If the customer balks at this, then you might want to think about getting some new customers. There is no reason why you should have to pay for this out of your own pocket. I prorate the cost of the tapes and coroplast and charge shop rate for labor in the layup.

You are essentially giving the customer superior edge quality for just a few bucks more than a hack job and tabs. Something for you to consider.

-B

[dana_swift]

Brady- that is an excellent technique. Thank you for sharing. I can see where that could be very useful in my applications.

I can see a rich area to explore there for holding down all manner of parts.

Good thinking!

D

[knight_toolworks]

this may be better then contact cement. think it would stick to wood?

[Brady Watson]

Thanks guys. I'll get some pics together as soon as my life simmers down a little. This method works unbelievably well, compared to every other method of hold down when doing thin or small parts. I have literally cut hundreds of thousands of parts with this technique.

Steve - I have used it for solid & sheet/plywood type material up to 1/4" thick. I'm not saying that it wouldn't work for parts thicker than this, but you have to stop and think about the physics going on in the cutting process. The thicker the material, the greater the force that can potentially be exerted against your hold down method. Even with conservative step downs, it is possible for a spiral bit to lift the material in such a way that it causes the transfer tape to fail. So using thick materials with this method is something you guys should try out - and then report back to the group to share your findings.

Non-porous materials are not a problem. Woods and other porous materials should be cleaned religiously and tested for adhesion. Veneers of any material are a cakewalk with this system. It is VERY important to use a j-roller to really get these sheets to stick together. A professional lamination machine is really the best...but don't bother unless you already have one in your vinyl shop.

-B

[kra]

i used your method today to cut 1/4" pvc and it worked great
a less aggresive application tape seems to works better with pvc
it really sticks to the raw pvc

I ran my cut file again to clean up the welded shavings and nothing moved even though some of the parts were less than 1/2" x 3/4"
almost no sanding

great tip! thanks

[john_l]

Quite a testament Randy.. 1/2 x 3/4" is really small!

Brady, Thanks for posting the tip. I have been using almost the same method except that I usually use our "Premier" Contact Adhesive spray setup instead of your double sided tape layer. This contact cement is pricey and may not be saving me any material costs but I do think it may be faster. But thats only cause I have it here already.

Do you apply the double sided tape (6" wide roll) continuously over the full area you plan to cut? Even if done that way, you could still get about 3 full sheets from a 72 yard roll.

And I fully agree about charging for ANY necessary hold-down, clean-up, or any other reguired procedure regardles of what it might be. I do here, at full shop rate, and I hope all others are as well. Please dont give it away!!

[Brady Watson]

Randy,
Glad you were able to test it out! Yes - On really smooth plastics etc, the transfer tape really takes hold. BUT...the good part is that it comes off of the finished part easy enough to not damage or kink the part. This is really helpful on thin aluminum, where carpet tape would just ruin the parts because there is no way around not bending the AL to get it off the table.

John,
I have used contact cement as well, and it winds up being a bit cheaper than the tape. I didn't want to have to mess with cleanup or kill myself with the fumes. There are some good low odor water based contact cements out there, but unless I am doing 5+ 4X8 sheets, then setting up for it isn't worth it. I just use the tape.

HINT - Try cuttings some 1.5" tall letters using this method. :D Sorta opens up a whole new realm of things you can cut on a ShopBot doesn't it?

-B

[ckurak]

Brady,

Thanks for sharing! Now, I have a few questions when you have some time.

1) You mentioned that this method works for "thin wood veneer" as well. Exactly how thin? Standard commercial veneer is about 1/40th of an inch.

2) How small of pieces did you try cutting in veneer? I sometimes have pieces that are about the size of a small child's fingernail.

3) I do not have vacuum hold-down on my PRT. I usually use screws. My thoughts are that a) the pieces that I will be cutting will be relatively small. That is, anywhere from smaller than a dime to about 15". b) I could simply use the same materials as you suggest but screw the coroplast to the spoilboard instead of using vacuum. Your thoughts?

4) What thickness coroplast do you use?

5) I believe I understand your description, but photos are always nice. :)

Thanks!

[Brady Watson]

Brady,

Thanks for sharing! Now, I have a few questions when you have some time.

1) You mentioned that this method works for "thin wood veneer" as well. Exactly how thin? Standard commercial veneer is about 1/40th of an inch.

2) How small of pieces did you try cutting in veneer? I sometimes have pieces that are about the size of a small child's fingernail.

3) I do not have vacuum hold-down on my PRT. I usually use screws. My thoughts are that a) the pieces that I will be cutting will be relatively small. That is, anywhere from smaller than a dime to about 15". b) I could simply use the same materials as you suggest but screw the coroplast to the spoilboard instead of using vacuum. Your thoughts?

4) What thickness coroplast do you use?

5) I believe I understand your description, but photos are always nice. :)

Thanks!

1) As thin as you can get it. You could probably hold down tin foil.

2) The last I recall is about 1200 parts @ 3/8 X 3/4" with a 1/16" bit. It boils down to machine resolution at that point.

3) Screws = Bad News. If you have a shopvac, and some scrap, then you have enough to put together even a rudimentary vac setup. Have you at least tried some type of vacuum hold down? If not, you are missing out big time! Anyway....Just use carpet tape on the back side of the coroplast to mount it to the spoilboard. Screws and small precise parts should never be mentioned in the same sentence, when it comes to cutting.

4) The cheap kind....4mm I believe. Don't get stuck on the 'it's gotta be coroplast' thing. It is cheap and available for me...you can just as easily use scraps of PVC or whatever you have laying around. Stay away from woods if you can.

5) Yeah...

-B

[wberminio]

Thanks Brady

You just opened up a whole new world..........http://www.talkshopbot.com/forum/images/icons/icon14.gif

[kra]

I cut out a couple of 6" letters from 1/8" pvc and used scrap 3/16 foam board for backer instead of coroplast and it worked pretty good too

thanks again Brady for sharing a great way to hold parts

[knight_toolworks]

I can cut sintra and dibond most of the time with just vacuum. using a 1/8" straight bit the shavings will keep the piece in place. acrylic and lexan don't work as well.

[Brady Watson]

No problem guys.

Hey - If you guys have the chance, can you post up a few pics of what you are cutting here? I think that it would be of help to all to see a visual of what the process entails. Nobody cares if they are crappy...and if your shop is a mess. Pics...

I swear I took pics of a really tightly nested sheet of acrylic parts that I did...but who knows where they wound up. Anyway, here's a pic of me laying up the tapes:

http://www.talkshopbot.com/forum/picture.php?albumid=21&pictureid=115

Towards the bottom of the sheet, you can see the two 24" widths of transfer tape that were applied to 3/16" Acrylite. I left the Acrylite paper protectant intact. Then towards the top, you can see where I've run the 6" mounting tape. The roll of 6" is sitting on top of the waxy mounting tape backer paper. I leave about 1/4" in between 'tracks' to keep me from overlapping the tape. Care must be taken when applying the mounting tape because it grabs hard enough to pull up the transfer tape if you start pulling it the wrong way.

-B

[geneb]

Here's an example of something I did that's very similar to the method Brady uses:

http://www.simpits.org/geneb/wp-content/uploads/2009/12/almost-finished.jpg

This photo shows me cutting a control panel & connector bracket out of .062 6061-T6 aluminum. Instead of using tapes to hold it in place, I sprayed the black base (UHMW) and the aluminum with Wilsonart formica spray adhesive. I let it sit for 30 seconds or so (I don't recall the exact time, I just followed the instructions on the can) and then mated the parts and hit it with a J-roller for a few minutes.

The metal parts popped right off with a little effort from a flat bladed screwdriver and cleaned up quickly with some Simple Orange.

The UHMW base is held in place by vac - there's a rubber gasket in my plenum that you can't see. I also used my spoil-board cutter on the plastic before I glued it up - I didn't want to cut that deeply into it. However, next time I'm going to try the coroplast trick. It looks to be much more economical than using my UHMW scraps. *laughs*

Here's a pic of the finished panel if you're curious:

http://www.simpits.org/geneb/wp-content/uploads/2009/12/left-sub-panel1.jpg

The white paper is a laser cut version of the final acrylic edge-lit panel.

That was also cut using the same spray adhesive method:

http://www.simpits.org/geneb/wp-content/uploads/2009/12/left-sub-panel-light-plate-is-cut.jpg

g.

[woodturner]

I'd like to ask for some advice on this technique please. I need to cut a bunch of small (7" +/- long, and tapered from 3/4" wide down to 1/4", think small triangle) parts in 3/16" thick polycarbonate sheet.

My supplier only has the PC sheet with "cling" film to protect it, not the sticky paper like acrylic. And, I am afraid acrylic is too brittle for the application. Has anyone tried sticking the wide transfer tape directly to the polycarb, then gluing that to the corplast? I am set up for spraying contact cement, so I planned to go that route. Will the tape hold the parts and release them OK? Will the contact hold the back side of the tape? I don't have the double sided stuff.

I plan on cutting with an Onsrud single flute at 2" per sec, probably offsetting the first cut and then doing a .025 clean up pass. There are a few tight curved areas, so I might path those separately and go a little slower (rpm and feed). I need a very good finish (flame polish???) since it's for a display. Any thoughts are appreciated!

Kind Regards.

[Brady Watson]

Gene - Looks great. The only thing I would add is a 1/4" or wider 'island' in the center of the vac pocket you have machined there to prevent the material from cupping down when under vacuum.

Ed - You should have no problem cutting those parts with transfer tape right on the acrylic. It is a bit tricky to get a nice smooth lamination because the transfer tape really sticks to the acrylic's ultra smooth surface. It peels off easily though.

Experiment with the transfer tape & your brand of contact adhesive on scrap before you try it on the real deal. I don't see it being a problem as the transfer tape should act as a barrier for the cement bleeding thru. Acrylics are sensitive to many solvents - which *may* be flashing off of the contact adhesive...Test it to be sure.

I would cut these small parts in 2 passes with a single spiral-O flute at 1,0.5 with ramped entry at 18,000 RPM or a double or triple spiral-o flute up to 2 IPS, if the cutter diameter is at least 1/4". Test 1st few to dial it in & adjust accordingly. You may be able to get away with a single pass, but you'll have to test to be sure. No two acrylics cut the same...and color can greatly affect cutting speeds. Check it: http://www.plasticrouting.com (http://www.plasticrouting.com/BitSearch.asp?Page=Material)

-B

[tracys]

Thanks Brady!

[woodturner]

Hey Brady,

I'll say "thanks" as well. I got to try it today (prototypes) and only one part lifted during the cut, and it was the part nearest the edge. Again, I'm cutting polycarbonate (Lexan), and my cut quality was poor. A lot of chatter marks. I may try again tomorrow and go slower.

The tool diameter is only 1/8" for some tight areas I need to cut, and 3/16 for the majority of the cut. I am using arc/mm for the post. What is interesting is the portion of the cut that is truly a straight cut (in X) doesn't look too bad. But the sloped cut (third side of the triangle) or wherever there are curved areas, the cut is very "bumpy." I wonder if it is chatter or resolution. And unfortunately, I was aiming to make it more curvy because to straight section looked too boring. Again, this is an Alpha and spindle, and the part was designed in A'cad LT and imported into Insignia. Any ideas as to improved cuts?

Thanks again in advance for any suggestions!

[paco]

Hey Brady,

I'll say "thanks" as well. I got to try it today (prototypes) and only one part lifted during the cut, and it was the part nearest the edge. Again, I'm cutting polycarbonate (Lexan), and my cut quality was poor. A lot of chatter marks. I may try again tomorrow and go slower.

...

Any ideas as to improved cuts?

Thanks again in advance for any suggestions!
With a finishing passe.

[woodturner]

Hello Paco,

I should have said, it was with a finish pass. My first pass left approximately .040 thickness from the bottom and .020 from the profile. The "finish" pass was at full depth and (theoretically) cut only .020 from the part. Again, way too many marks. Could it be poor circular interpolation? I thought the alpha using the arc/mm post performed that alright. It looks like the proverbial mini X and Y steps to cut an angle or curve. Any suggestions as far as settings to change for cleaner cuts?

Thanks in advance!

[Brady Watson]

Ed,
I'd try slowing lightening the chipload - or bite that each flute takes per revolution of the spindle/router. You can do this a few ways...

1) Increase RPM
2) Reduce Move Speed
3) Use a 2 or 3-flute spiral-O (Onsrud 65-624 or similar)

You should put your safety glasses on (with side shields!) and get in there and observe what is going on as the parts are being cut. Are they lifting? If so, and you have reduced chipload without melting, it could be that you either don't have enough vacuum pressure or that the helical flutes of the tool are working against you - causing lifting. ANY vibration from parts lifting even a little bit, will degrade the cut quality. Parts should NOT be moving if you are using the technique & materials I outlined above. Substitutions for other products or methods will give varying results.

If the spiral tools are lifting parts & you've done all you can do, try a 2-flute straight-O tool, which will leave chips in the kerf, aid hold down and still give a decent cut. I would not advise using straight flutes on plastic over 1/4" though, because you really want to get those chips out of there.

Reduction in cut quality is in most cases, directly associated with worn pinions and dry gear racks...You'll also want to check the machine under power, not moving, by grabbing every axis and push/pull - listen and feel for slop in each axis. Really shake everything and listen for the tell tale 'ticking' of slop. I am not talking about the slight ticking that you hear from a 7.2:1 gearbox - this is normal. Check the v-rollers...Clean each and every rail with a scotch pad - every little bump in the rail will transfer to your cuts.

You should be running those small bits between .5 & 1 IPS and 18,000 RPM. If you are not, your chipload is probably too high.

-B

[knight_toolworks]

I have been cutting a lot of lexan lately. some really thin .03 stuff. but even with a custom vac setup and very strong vac these things move a bit. a simple solution was spraying the vac bed with contact adhesive. that would lock them in place.

[Brady Watson]

Steve,
You seem to have missed the point of the technique...Spraying glue right on the bleeder is a sure way to seal it and completely defeat your efforts... :rolleyes:

-B

[knight_toolworks]

I had holes for the vacuum. but even with the very strong vac the lexan would jiggle. so the spray made things non slip.
I just had to cut 8 more sheets so I just vacced down a piece of 1" mdf flattened it and used the spray on both sides. but this only worked because of hte size of the pieces and that they were so thin.
I am waiting for the pressure foot and then I can dump the spray all together.

[knight_toolworks]

I forgot I had to cut 4 full sheets of thin lexan and nothing on hand. so I just sprayed the spoilboard with 77 and used my vac too no parts slipped though I used the spoilboard afterward without a problem it was nicer to surface it first.
this is a messy fast solution but it does work for thin plastics.

[woodturner]

I will try cutting again and go a bit slower. I was at 18K rpm (my max) and 2" per sec as per the folks at Onsrud for 3/16 polycarb. And again, my true straight cut (straight move in X) was pretty flat and smooth. It was the angled and arched cuts that were bad. The was no re-melt which is good. I have had problems with that in the past, mainly with acrylic. I'll also make sure everything is tight (although I do this routinely). For what it's worth, my tool isn't likely to have anything "worn" on it since it get so little use.

Also, what type of pressure foot are you referring to? Is that like a roller hold down of sorts?

Thanks!

[woodturner]

Another thought!

I reviewed comments on polycarb cutting about 10 posts down. I looked at my geometry in Artcam (insignia) and the angle and curves looked segmented. I just always assumed that's a graphics limitation. Could I be creating lines instead of arcs? Although, my angled line looks segmented as well. Only my straight line in X looks truly smooth on the screen.

As mentioned previously, I am creating in Acad LT, importing .dxf into Artcam, then tool path using arcs/mm.

Once again, suggestions are appreciated.

[bob_s]

Ed;
I don't use Autocad LT, but some designers I cut for do. I have seen some lines that I think they intended to be arcs come into Aspire as segmented sections. I replace them with arcs or Bezier curves. On other drawings I believe they have been arcs when they imported, so I am guessing it depends on how Autocad is setup to export or save a file?

[knight_toolworks]

I have been only using straight bits for the thinner plastic polycarb for sure. the smaller the bit the better. usualy the shavings don't reweld. I cut 8k at most. I was cutting some .03 lexan yesterday with a 1/16" onsrud 1f straight bit at 3ips and 10 or 12k. I used spray adhesive on both sides because the parts were small.
52 parts per 2x4 sheet.
Now I cut a full sheet of .5 lexan using a 1/4" o flute upcut in two passes at 1.5ips and the last pass was really vibrating. the peices were about 14x18 and the vac could not hold them down. I think this is a real issue with lexan it seems more grabby then most other plastics. so the straight bit really helps in through cuts.
Widget works if he ever gets his rear in gear (hey just joking) is coming out with a great (from what I have heard) pressure foot that will let us cut parts down to .25 square.

[woodturner]

Steve, I think you're right about the particulars of Lexan. I know it's considered a "soft" plastic to cut, even though it's "tough as nails." I think that does make it grab more. Also, when I've cut .5" lexan, and I remove a considerable amount of material, the sheet seems to curl (stress relieve?) up and off the table,,,,,,bye bye vacuum.

I am going to try .125 Lexan on Monday and see if I get acceptable results over the .187 I've been playing with.

[Brady Watson]

So...From what I gather, reading the last several posts, questions are being posed in this thread by people not actually using the technique from post #1. This is truly amazing to me...

If you use the technique as it was designed & written, then you will not have parts lifting, you will not have sheets curling as they are cut and other issues. I'm sitting here reading, thinking both Steve & Ed are using the VF Technique, and then we are spraying bleeder boards with glue and doing other things...If this is confusing me while reading, then it would not be a stretch for someone new to vacuum to get completely confused, lost and mis-informed.

Correct me if I am wrong in my assumptions.

Like anything else I post up from my own R&D, I only ask in return if you use the technique, share your experience & post pictures for others, further advancing our efforts and progress as a group.

-B

[knight_toolworks]

I want to use your methods. but I don't know if I could bill it. most of what I cut with the spray adhesive has been just simple cheap parts out of thin plastic. but it looks like lexan needs all the help it can get.
but the spray adhesive is dirt cheap and fast.
but as soon as the pressure foot is out I won't need it anymore.
if I ever remember to order the materials i would try it.
I had to cut 8 sheets of 2x4 .03 lexan yesterday. I vacced down some mdf flattened it out and spray both pieces lightly and cut it one sheet after another. I was actually cutting 3ips with a 1/16" bit and never lost a piece. Now this method would not work always and would only work with a straight cut bit.

[woodturner]

Hey Brady,

Let me clarify. I tried the technique on my 3/16 lexan (not acrylic) and as I previously stated, and thought it worked great. I only had one part lift off the tape. Also, remember I had to apply transfer tape directly to the lexan since it was not covered by a protective paper, but rather a "cling" film. I then sprayed contact cement to the back of the transfer tape since we are "set-up" to spray contact and don't stock double sided tape. For what it's worth, I think the spray glue is faster for us, contributing to lower cost.

I am going to try it again tomorrow using thinner (1/8") lexan in the hope of a better finish. I would not have tried either of these without you sharing this technique. If I have better results, I'll share that information as well. What I should have done was start a new thread addresing the machining issues of Lexan.

I don't think my parts (other than the one previously mentioned) moved. I think I have other things at play (X and Y steps rather than true arcs) that I don't really know how to solve. Part of it may be that, since lexan is expensive stuff, I am trying to nest parts as close together as possible, leaving just enough room for the cutter to go by. That obviously means that after the one part if cut, the next path is cutting mostly air. Perhaps this is contributing to chatter. But, again, I did it in two paths with the finish pass cutting around .020. I would think that would "clean it up." I could be wrong and still getting bit deflection.

Lastly, when I responded to Steve about my experience cutting 1/2" lexan, I should have stated that was around six months ago and I had no other plan of attack other than just suck it down with the pump at the time.

I hope that clears it up.

Thanks Again!

Ed

[Brady Watson]

Ed,
Thanks for the feedback. So the spray glue worked fine & didn't bleed thru the transfer tape then? What brand did you use? 3M 77/90 ?

In terms of chatter, make absolutely sure that your motors are fully engaged in the racks (on PRS) - provided that your R&P are greased and relatively new.

Also, make sure you are using the Arcs_Inch post processor instead of the regular Inch one. This will smooth out curves, but not straight diagonals. Of course all of this goes without saying that if you have extra or jagged nodes in the artwork, they would also be a factor.

Thanks!
-B

[woodturner]

Brady,

I will have to check on the contact glue. We buy it in the propane style tanks from our laminate supplier for around $250 per canister. I think this one was from Web-Don (our Wilsonart Supplier).

I am using the arc/mm post. I removed the other posts from my options a long time ago.

My racks are greased, the motors seem tight (I can't move them at all when powered up).

As far as extra or jagged nodes, I am not sure how to tell if that is the problem. As stated previously, I am creating the geometry in Acad LT using lines, fillets, arcs created from three points, offsets, and trimming accordingly. I can "zoom in" all I want and there are no wandering points or anything like that. I do see segemented arcs and angled lines. I had always assumed that was simply the resolution of the graphics and NOT anything that would create a problem with the tool path. Now I am not so sure!

And by the way, I didn't get to run the addtional parts today, but I'm shooting for tomorrow.

[widgetworks_unlimited]

Brady's vacuum film technique has worked well for us in past applications. I'm sure many folks can benefit from having it in their clamping arsenal.

Ironically, a few weeks before Brady first posted to the forum describing this method, I had designed and started using a new "pressure foot" clamping attachment. It allows you to clamp and cut many of the same parts that would require a vacuum film technique, but with our pressure foot you don't need the transfer tape, double-sided tape, or backing material. For many parts you don't even need a vacuum table.

I don't want to sidetrack this discussion away from "vacuum film clamping". If you'd like to hear more about our pressure foot, here's a link to my full post in the product listings section of the forum. (http://www.talkshopbot.com/forum/showthread.php?p=103239#post103239)

It's been hard as heck to keep quiet - watching this discussion while testing our prototype and getting our first production run of pressure foot attachments ready for sale. I didn't want to discuss them on the forum until I was sure we had something that would provide a real benefit to others.

Here's a sample photo of .010" aluminum that I've wanted to share with the forum for the past 3 months... I was smiling ear to ear when I first cut this - no tabs/post processing required. Ready to go straight off the machine.

- Russ

http://www.widgetworksunlimited.com/v/vspfiles/photos/CNC-PRESSURE-8.jpg

[Brady Watson]

Looks great, Russ. Thanks for posting.

Know what you mean about keeping quiet during R&D sessions...

Keep up the good work.

-B

[xbinbc]

Thanks so much for this method. I cut a full sheet of 1/4" cast plexi this way today. 6" nested letters. Edge qualiy was excellent, not one letter moved. I have to find a canadian source for the mounting tape. I also had to use spray 77 glue between the transfertape and coroplast. No tabs
& no need to worry about the insides of text flying around!
Totally impressed

Jon Shoring
Signfast Custom Signs
Vancouver Island
Canada

[knight_toolworks]

you got to invest in the pressure foot. I have cut some very small parts and don't loose them. about all I have not been able to cut were these squares that will about 3/8" square. I still need to vac the material down but now I pretty much cut without any extra hold down.

[geneb]

Because the forum software is mis-configured (only allows four image links per post), I've written up what I did when following Brady's technique here:

http://www.geneb.org/shopbot/cutting_alu.html

thnx.

g.

[Brady Watson]

Hey Gene - That's a nice write-up. Thanks for posting!!!

-Brady

[geneb]

You're quite welcome! That same double-sided tape you recommended for this project is also what I used for a big collimating mirror project. :) I'll post a big spread on that in the Show And Tell forum as soon as the 4-images-per-post issue is fixed.

g.

[jim_vv]

Greetings, Brady

Thank you for sharing your Vacuum Film Technique. I ordered the transfer and double sided tapes from Harbor Sales which only took two days to arrive. I followed your suggestions today for cutting lots of tiny sign parts from .5" Gatorfoam. It was a great success! Thanks again.

Kind regards,

JIM

[Brady Watson]

No problem, Jim. Thanks for saying thanks.

Oh...you can get that other tape I mentioned via PM from Harbor as well.

-B