www.TK560.com

[speedofsound]

Hello, my name is Alan. I've been scouring this forum for information regarding vacuum forming, and I'm very glad to find you guys/gals! Lots of great info in here, no doubt.

Over the Memorial Day weekend I decided to build a quick, small-scale vac former for the purpose of rapid-prototyping. A large/fast setup isn't really required for my needs, but we'll see...

So far, I've spent about $120 and about 4 hours on this "experiment". I found a slightly damaged 30" base cabinet at Lowe's, and thought it would look nice in the shop, also saving me the time of building a 2x4 frame. Vacuum is a Lowe's 5.5 hp shap vac, bag removed.

Based on my reading here, I went with the single-hole platen. I used some scrap aluminum sheet from the shop, and milled some 3/4" MDF to recess the metal. Used some plastic welder adhesive to mount the vacuum coupler to the platen, then ground/sanded it flush.

Built a temp frame to test, more permanent one will be built when I get some more plastic. Size is 12 x 16 now.

Talk is great, but pics are better, right?







Feel free to laugh at my "oven". I used a heat gun on the top side...



First pull!



Material is .090 ABS. Didn't pull the edges quite tight enough, but I feel the problem is *mostly* in the draft angles on the mold. I'm tweaking these today, and will try again.



2nd pull! Struggled a little bit with this one.







Your feedback will help me a lot! I could really use some advice on a top-mount oven. My budget may allow me to *not* have to build one, but I'd be interested in any thoughts and will probably pepper you guys with questions!

Thanks,

Alan
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[mrbungle]

very cool. what thickness of plastic are you using??
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yes, my name is mrbungle like the band...............

[jdougn]

Hey Alan, welcome to the forum and thanks for such a great post of your project! Looks like you have a good shop setup and built a very clean first effort vac former.

Looks like the first pulls with the .09 ABS didn't turn out too bad. But it looks like they had some "undercuts". Were you able to get the originals removed afterwards? Also, in my limited experience using 1/8"-1/4" ABS, lack of detail is often caused by inadequate vacuum or the material needing more heat before forming.

For the oven, go with Hardibacker from the tile department at Lowes. Then, use 22 gauge nichrome wire available from Mor Electric http://www.infraredheaters.com/nicrcoil.htm. If you really want to build a nice vac former use plans (I wish I had!) http://www.build-stuff.com/index.htm.

Keep posting up your stuff! It's always interesting to see what others are doing and the successes!

Doug
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DougN - Just in case you're wondering, I got my "rating" legitimately... by posting aimless drivel, useless advice, and pointless questions.

[jegner]

Those molds look great. the base edge detail is vague because the shop vacs have a hard time holding ABS while the plastic cools. You can test your molds with HIPS, or you will want to consider going with a high-vac setup if you plan to use ABS. You can try daisy-chaining a couple of shop vacs together for a slightly better pull, just be sure to draw one from the other and be sure everything is sealed up, but honestly, a hi-vac pump and tank are the way to go when forming ABS.

Another thing to consider is the oven. It's really easy to make one that will properly heat your plastic, but considering the size of your platen, I would suggest a kitchen oven, racks removed and a custom holding frame installed. You should be able to pick up a used oven on the real cheap. This will give you much better heat control.

Very cool project you are working on! Thanks for sharing the pics.

Jim

[speedofsound]

Thanks for the replies, awesome info!

I had a feeling the shop vac was a main cause of the ABS not giving me the edge detail, but I also felt the mold had some really steep edges (no draft, or even negative draft) so I've fixed that. I'm going to pull the mold again and see if my results change at all.

I've spent some time at the infraredheaters website, and am curious about some of the pre-made heaters. Anyone have experience with any of these? The prices don't scare me too badly, and I'm honestly a little nervous about the hardibacker oven (and MY building it, lol).

The smaller (black) mold was difficult to remove. The bondo mold (white-ish) comes out pretty easily, although the "parting line" I'm after is not very defined. I would like to get it easier to see, as I'd prefer to trim this by hand and not go to a more complicated CNC trim program.

I can see myself going to a hi-vac setup pretty quickly. I have a vacuum pump, but don't know the details on it. I can post a pic/info later.

I really appreciate the help, thanks!

[jdougn]

Hey Alan,

If you want a well made oven then go to the Build-Stuff site. They sell oven kits specifically tuned to heat plastic which is important. They use the nichrome wire with ceramic backer boards IIRC. If you get plans then you don't end up having to re-invent the wheel so to speak. In my experience, there are way too many technical details to get them all right the first time on your own. I would've spent less money, less time, had less frustration, and had a better vac former if I'd just got the plans.

For cut outs consider using a wood pattern and a trim router with a guide. If you can go with a vacuum pump/tank you will be much happier with the results. My 2'x4' vac former uses a hvac evacuation pump rated at 10cfm connected to a 30glln tank. I got the pump used for less than $300 through a local industrial equipment recycler.

Hope this helps! DougN
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DougN - Just in case you're wondering, I got my "rating" legitimately... by posting aimless drivel, useless advice, and pointless questions.

[speedofsound]

Thanks for the very helpful info!

I've got an old Gast vacuum pump in the shop, but don't have a tank. Considering my part size, and what I've read on here, can I get away with something in the 10-20 gallon range? It would be nice to fit everything in the base cabinet.

About the oven: I saw a machine on Youtube from Spektr (he posts here I think), and really liked that oven setup (the whole machine, actually).

I plan to use 80/20 extrusions to run my frame from heater to platen. I saw Spektr uses pneumatic cylinders. I had actually been thinking of using electric actuators, but they may be too slow. For starters, I'll probably slide the frame manually.

Unfortunately I couldn't do much work on the machine this week, due to a double-whammy of a 4.5mm kidney stone and a case of shingles! Yikes. I'm "pumped" about this project though, so there's more to come...

-Alan

[jdougn]

[speedofsound]

[spektr]

You need a tank to make decent parts. It's NOT a holding tank. The purpose for the tank is to provide for a vacuum resivior that will provide instantaneous flow rates far in excess of the pump capacity. When you look at the pumps delivery curve, it says 5 cfm AT AMBIENT. As it generates vacuum, its flow capacity drops a lot. At 25 inches, it will be far less than 1/2 cfm. This is why leaks kill a pump only setup. A vac pump cant cover a leak. A tank in the setup lets you get a few seconds of flow in the 50-60 cfm range, and hammers the plastic down on the mold before it cools and locks up. If you were to rely on a pump only system, or worse, a shop vac only system, you need to get the plastic hot enough to stay soft for a longet time. This means higher sheet core temperatures and along with that, a less forgiving forming window. You have less margin for process errors and a higher scrap part rate. Part to part variability is also more problematic.

you might ask while every commercial machine sold has a vac resevior tank on it..

Im not saying you cant have success with a tankless system, I am saying you will be much more limited in what you can achieve.....

Scott.

[speedofsound]

Thanks for the education, Scott.

I have no problem using a tank, but wasn't sure if it was completely necessary. Your explanation makes perfect sense to me, now that I understand the process a little bit more.

Are you the Spektr with the 2x2 and 4x4 machines on Youtube? If so, very nice work.

[speedofsound]

Scott, my apologies. I confused your username with something I saw on Youtube.

*This* is the machine I am referring to, as well as the oven. Is the infrared heaters site the source for this? Are there "turnkey" versions in the 2 x 2 size, or was the unit in the video assembled from "modular" parts?

http://www.youtube.com/watch?v=ZgvLjkLTet4

My intent to use 80/20 and linear actuators should mimic this design. I have a surplus of 80/20 in my shop, so it will go to good use and save some significant costs. I'll still pay through the nose for fittings, though.

Thanks for any input!

I'll post some pics tomorrow of the control panel I made today. I recessed the panel into the front "drawer" face on the cabinet. Used the CNC to do the engraving and cutouts for switches and a vacuum gauge. Had a little "oops" with the mill, so I'm going to have to cut another for the final version.

[spektr]

Dont Sweat the Small Stuff.

[speedofsound]

[speedofsound]

The usual "wait for parts" is in effect, but I've now get enough materials in hand to continue my shop's DIY vac former.

I'm using a pair of linear track actuators to raise/lower my frame to my overhead oven. Working on the oven now, as well as the rest of the framing.

The frame lowers tightly to the table surface (not shown in full *down* position below), and can clamp with 400 lbs of force. Speed is about 3 in/sec, so it will get to the mold quick enough for my needs (oven height can be adjusted, at least that's the plan). The individual hand controls will be deleted, in favor of two relays and a 3-way switch on the control panel.

Here's a few pics for your entertainment:











This is one of my prototype parts being tested "in-car", in this case a 2010 Ford Mustang.