72 replies to this topic

[Gene/ZR1]

I have received a lot of questions on vacuum forming and mold making for Thingies.

 

If you are interested on the above subject I will take you all the way from a reliable home build vacuum form table to simple mold making and vacuum forming a body. 

 

This will get the hobbyist meaning you, going in the right direction and not spending time and money on failures. 

 

Q&A are more than welcome.

 

I will post what you need and sources and how to get started. 

 

We will start with the vacuum table.

 

Let me know if you think it would be worth the effort.

 

 

regards; gene

[Bill from NH]

I think it would be worthwhile. Even at my age, I enjoy learning something new.

[Samiam]

 

 

Always interested in seeing how it's made. Even if I never get to make my own bodies it's cool to see how to make the machines and tools that make our little cars. 

 

 

[Pappy]

I've been gearing up and getting ready for my first try at it. I've talked to Billy Watson on how to do it and I've watched some video's on U Tube on how to make the machine and heat the plastic but I'd love hear what you say about it.

[Jaeger Team]

very interesting topic 

[mark1]

Sounds good! go for it.

[SlotStox#53]

Sounds perfect! Go for it, have your other how to bookmarked and pictures saved. But always room for more information

[MattD]

Go for it Gene.

[Thom]

For those of us that want to pull a few bodies for our own use, this is going to be educational !!!

[Half Fast]

Definitely go for it!!

 

Cheers

[Gene/ZR1]

Let's get started;

 

(Just remember this is for slot car bodies)

 

If you have a vacuum table and having issues pulling bodies, post your issues.

 

Most hobbyist will spend money and time and end up with wasted materials and disgusted with the results they are getting with no end in site.

 

Suggestions;

1.Start with easy materials,  use 0.020 PETG, forget the high price spread Lexan for now.  

2.For the vacuum source use a vacuum pump, forget the shop vac, put it in the garage.

 

For the beginner or the failed hobbyist ready to give up.

 

 Doug Walsh lives about 8 miles west and I needed a oven coil and he sold an oven kit and vacuum table plans. I went to his house to pick it up (about 12 years ago), I seen his 2 vac tables and was impressed. yep, I purchased his plan set and the oven coil.

Instead of reworking my oven area, I looked over his plan set and thought why not. So I built according to his plans.

 I did modify my platen and pattern and prefer mine.

 

So my suggestion is this go here;  

http://www.build-stu...ng-build-plans/

The plan set is a no brainier very complete and plenty of photos.

 

Purchase the plan set and oven kit, build it by following the plans keeping in mine you will use a vacuum pump only.

I have made some modifications that I will share, the whole purpose is to get you the hobbyist up and going in one week and to avoid failures. Once you have your vac table working contact me and I can send you a couple of resin plugs ready to test pull some trail runs, postage will be on you.

 

This is a Thomas pump, it will suck the chrome off a bumper.

 

the 2 photos show the backbone, the vacuum pump, clear connector hose and the platen.

The platen has to be constructed correct, no short cut on this.  

 

Were just getting started, so Q & A  time.

 

regards; g

 

 

 

 

 

 

[MattD]

I know it's a lot of work to do this, but it is clear and easy to understand.   Thanks Gene.

[Thom]

I have a good idea of what the particle board looks like under the aluminum plate,
do we need to buy the plans or can you show us or give us a drawing?

[Gene/ZR1]

john;

 

Excellent question;    Shop Vac  vs  Vacuum Pump

 

In the photos, the platen; under the metal plate with the holes is a metal mesh screen that elevates the metal plate so air can enter and pass thru when the vacuum pump is turned on. Also note a thin dark line, that is silicone that seals the perimeter from air leaks, air must pass thru the platen holes only when the pump is on.

 

 Study the setup as shown, notice the amount of area that has to be vacuumed before a negative pressure is achieved to start the forming of the plastic over the mold, this all takes in about 2 seconds or less.

 

 A shop vac can not compare to a vacuum pump. 

 

Study the metal platen compared to a peg board box platen box connected with a large shop vac hose along with the volume of the shop vac canister. When you add up all of the volumes; vac box, vac hose,vac canister, before you even start to draw a negative pressure all this volume has to be eliminated before your plastic even starts to pull over your mold, by then your plastic temperature has started to cool.  

 

The vacuum pump, platen set up as shown, all you have is 30 inches of 3\8" round clear hose. 

   

 

gene

 

 

Attached Images

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[olescratch]

Thanks for the reply Gene, I removed my post once I read the lead you provided concerning the pumps.

[Gene/ZR1]

I have a good idea of what the particle board looks like under the aluminum plate,
do we need to buy the plans or can you show us or give us a drawing?

Thom

Here is a simple cut away view, will this help?

 

Blue tape = area of silicone seal

Metal Grill = found in store barbecue area

Metal plate = duct sheet metal

 

g.

[olescratch]

Thanks for the example of the construction of the platen, I thought there would be a lot of holes to be drilled!  Would it be possible to use a pre-drilled piece for the top also?

[Gene/ZR1]

Thanks for the example of the construction of the platen, I thought there would be a lot of holes to be drilled!  Would it be possible to use a pre-drilled piece for the top also?

 

John

My platen is 8" x 11-1\2"

I would follow my hole pattern. (no holes within the silicone seal area)

Because when you place a mold on the platen, then you mask off all remaining holes, by doing so you will pull the air to the sides of the mold and in return more air will pull thru the draw holes in your mold picking up the mold detail.

 

   

platen masking (blue tape)

you can see how tight the plastic has drawn down, 90 degree to the platen base. Some hobbyist end up with a curve in this area.

 

g.  

[Gene/ZR1]

I have a good idea of what the particle board looks like under the aluminum plate,
do we need to buy the plans or can you show us or give us a drawing?

Thom

If you or anyone starting from scratch I would suggest Doug Walsh plans, they are reasonably priced.

g. 

[slotbaker]

Great tutorial.

 

Can you give us an idea of what spec to go for in a vacuum pump?

 

And, would there be any advantage of using a resovoir tank to build up the vacuum using a smaller pump?

 

[Gene/ZR1]

Great tutorial.

 

Can you give us an idea of what spec to go for in a vacuum pump?

 

And, would there be any advantage of using a resovoir tank to build up the vacuum using a smaller pump?

 

 

Thomas vacuum pump 2660 series (3.73cfm), note; make sure it has the start\run capacitor included.

 

 

e-pray example;      ~prices vary~

https://www.ebay.com...cAAAOSwintXSFJO

 

A:  reservoir tank , I do fine without one, as I only do slot cars and interiors.

 

regards ; g

[Pappy]

Gene,

 

Can you have too many holes?

 

I drilled 1/16" holes about every 1/2" around my mold and tried to pull a body in .030 PETG and I didn't get very good results.

[Gene/ZR1]

Gene,

 

Can you have too many holes?

 

I drilled 1/16" holes about every 1/2" around my mold and tried to pull a body in .030 PETG and I didn't get very good results.

 

Pappy;

You can always shut down holes you don't want by using non-hardening model clay. 

Later you can push it out with a piece of piano wire.

 

 If possible could you post a photo of you mold setting on your platen and your petg body.
 

0.020 petg if your new at this, at least until you get the hang of your system.

 

Let's figure out whats going on and get you up and running.

 

regards; gene

[Pappy]

No way for me to post a picture, I don't have a camera that I can download a picture to my computer. 

 

I taped over all the non-essential holes and it actually made it worse. I heated the plastic until it just started to sag, approximately 1 minute.

 

I managed to scavenge an old vacuum pump that looks like yours but I'm not sure it has enough suction. My platen is a wooden box about 4"x 9"x 2" deep.   

[Gene/ZR1]

No way for me to post a picture, I don't have a camera that I can download a picture to my computer. 

 

I taped over all the non-essential holes and it actually made it worse. I heated the plastic until it just started to sag, approximately 1 minute.

 

I managed to scavenge an old vacuum pump that looks like yours but I'm not sure it has enough suction. My platen is a wooden box about 4"x 9"x 2" deep.   

 
Pappy

 Without a photo it will be a little of a challenge but I will try.

 

a. When you heat your petg try and let it sag about 1-1\2 to 2".

 

b. Your wooden box to your vacuum pump must be sealed, meaning no leaks, seal any areas that may leak. It doesn't take much of a leak to lose your vacuum draw.

 

System Checking;

 If you don't have a liquid filled vacuum gauge to check your system you can do a simple system check by experiment.

Take a piece of Saran wrap and cut it so it will cover your platen laying flat. Turn your vacuum pump on, The Saran wrap should be stuck down on the platen, you can grab the edge of the Saran wrap at the edge and drag it off the platen just to see and get a feel how well the vacuum pump is holding the Saran wrap down on the platen, you should have a resistance.

 Also you can turn on your vacuum pump and take the Saran wrap and lower it to the platen, when contact is made your vacuum pump should labor.

 

c. Your platen width may be on the narrow side at 4" width. 

Generally for slot cars an all around platen size plate is 6" X 10" plus your clamping frame, so your cut plastic would be about 8" X 12".   

 Also by having cut plastic of 8" X 12" you have no waste when cutting your pieces from larger sheets. 

 

regards; gene