Mini Vacuum Table

[kayakerca]

I thought this plastic heating setup looked interesting.

Might even heat more efficiently with the lid over the plastic.

[Jason Rodgers]

This dude's registering method is super cool, but heating over a wok?!

I am re-building my vacuum table to incorporate features of the first video: larger holes in the platen, drywall sanding screen over the table, and an elevated, sealing rim around the edge of the table.

[Jason Rodgers]

Well, I got my new table arrangement assembled and tested it this morning. Gotta say, this is getting a little frustrating!

Here's the table:

I used 3/4" material for the sealing rim and pickup pug/buck/thingy.

Here's the first try:

This one wasn't hot enough (gotta pick up one of the IR thermometer guns at Harbor Freight).

Here's the second try:

Plenty hot, but thinned and tore through on the edge.

I think I'm asking too much of this little table. With the new sealing rim, there is at most 2-1/8" from the pickup mold to the edge, and 1-1/4" at the least. Asking the plastic to pull down 3/4" over that small an area is probably not going to be possible.

Before tossing the whole setup, I might try reducing the height of the rim. Otherwise, going to a larger table might be the only way I can get the results I'm after.

[Jason Rodgers]

After a few hours in the shop yesterday, I've made a breakthrough, and I now have a small collection of usable pickup covers!

First, here is the third and final "oven" configuration. So far, no problems with the gun overheating, and I've used it in this arrangement for 7 attempts.


The major leap forward was made when I built this ring to press the plastic down to the edges of the pickup mold. When I was watching those videos, the guys were pressing the plastic down with their fingers. At first, that seemed stupid, and would likely result in uneven thicknesses and other malformations. But I tried this with a piece of wood, pushing it down like a spatula, and it worked pretty well. I figured I could do this all at once with a caul, so I built the ring.


The ring is less than 1/8" wider than the perimeter of the pickup mold. When the plastic is heated sufficiently (and I figured out a repeatable schedule for this), I flip on the vacuum, and slip the ring on. It only takes a little gentle pushing to bring the plastic down the last 1/4" to 3/8" to the table, and the results are great!



It worked so well, I made all four covers that I need for this next batch of pickups I have planned. I was even able to re-form one of the sheets from an earlier failed attempt. (Five covers are shown, the first being the rather good result I got from just pressing down the edges with a piece of wood. Then I made the ring and busted out four identical covers in a row.)


So, I'm calling this good for now! Thanks so much for all the inspiration and advice, guys!

[John_H]

Way to go Jason. I'm glad that you've got it working. I hadn't considered pushing a form over the top, but I do give the plastic a push with my fingers. I've been using my TIG welding gloves for protection. They're thick enough for insulation, but are not clumsy. Thanks for sharing your results!

[Jason Rodgers]

Yeah, I'm happy with the results from this process, but I might try a different approach in the future. When I posted this over on the MIMF, someone suggested a vacuum pump for a stronger pull down. That, of course, is what is usually done, but the shop vac method has become the DIY vacuum of choice on the interwebs, so I went there first. As it so happens, I built a vacuum clamp/press system a few years ago based on joewoodworker.com parts and instructions. The reason I didn't use this was because my very basic understanding of thermoforming was that I needed a very fast draw down on the heated plastic. After my experience with these parts, I'm pretty confident that my vacuum system will work, and making a new table would be very quick and simple. Actually, while I'm building a new table, I might as well try switching to a new heat source: heat lamp for the main heating schedule, then follow up with the heat gun as needed. But like I said, I'm happy with my results for now, and need to do some winding! I've been a bit occupied over the past couple days, though, starting a 5-string fretless bass for a friend.

[tedmich]

Being almost 60, here's what I notice; These days people worry needlessly about kids. We can say that things were different back then, but they weren't. People are just paranoid these days. I had a man try to get me to go with him in his car back in the 60s, so that shit is nothing new. Now people don't want their 12 years olds to walk up the street alone. And as far as toys, I think it's more that the manufacturers are worried about lawsuits.

to be fair the kids who caught a lawn dart in the noggin are not posting to web sites; we are selecting for survivors here!

[copperheadroads]

Anyone know where to get CREAM STYRENE POLYSTYRENE PLASTIC SHEET

[Jazz P Bass]

Here is an EBay seller, although you did not indicate the thickness.

Creme Styrene Polystyrene Plastic Sheet 080" Thick 4" x 10" Lot of 10 Sheets | eBay

[copperheadroads]

Here is an EBay seller, although you did not indicate the thickness.

Creme Styrene Polystyrene Plastic Sheet 080" Thick 4" x 10" Lot of 10 Sheets | eBay

I have the seller bookmarked as it's the only cream sheets i could find on ebay .
I was looking for sheets around .060"
I am also wondering how close that cream sheet is to the cream color we find i pickup parts

[Jason Rodgers]

My TAP Plastics store has white HIPS, and I will probably play with some of that in the future, too. How does HIPS behave in comparison to ABS when thermoforming?

Regarding the cream colored stuff listed above, is material 0.08" (basically 3/32") thick any more challenging to work with than 1/16" stuff?

[jonson]

Hips is the first choice for vacuum forming available in all colours.

[Jason Rodgers]

Hips is the first choice for vacuum forming available in all colours.

Really? Why is that?

[John_H]

Anyone know where to get CREAM STYRENE POLYSTYRENE PLASTIC SHEET

I've seen it on amazon, and alibaba also. cream/ivory ABS seems to be more available in the USA

Really? Why is that?

HIPS is much easier to work with than other plastics.

Hips is the first choice for vacuum forming available in all colours.

I've had no problem finding black and white, but other colors are hard to get, or I'm looking in the wrong places.

[jonson]

Maybe it's a Brit thing but I'm sure most colours must be available stateside.. Stephen Webster Plastics