Just bought a vac-former - question for experts

Birdie

Birdie

Master Member
RPF PREMIUM MEMBER
I just picked up an old vacuum forming machine, a Clarke 917

DSCN21600.JPG


Everything seems to work okay, but when I turn the vacuum on, the suction seems very minimal - if I place my hand on the platen I can't really feel it, but if you place a piece of paper on there it does pull it down.

I don't have any plastic yet to test it, and haven't used a vac-former before.

Does forming generally require a lot of suck? :)angel)
 
My guess is that it has a small vacuum pump to draw the air out. You might not see a lot of volume of air moving, but it is how strong the pull is.

The best way to find out is to get some plastic and try it out.
 
It is possibly just the fact that you need to have something covering the sealing surfaces on the platen.

Any vacuum leaks no matter how small will add up to poorer performance.

Does your former have any kind of a vacuum gauge? If it does have a gauge then put on a piece of plastic and pump down to base vacuum.

A very primitve and easy check on all your vacuum seal - If you spray isopropal alcohol onto and around any sealing surface and your vacuum becomes worse on the vacuum gauge then you have a leak in that area.

If you think there may be a leak of sorts then clean all the sealing faces from the pump to the platen to make sure there is no dirt or grit on the seals.

I don't know much about vac forming but I do know a large amount about vacuum through working on high vacuum machines for years. Feel free to PM me if you need any advice or help.

Cheers Chris
 
Yeah nice buy ,how much did you get it for ,I been thinking of making one but if they are cheap to buy I may look around.
I imagine even if the suction is not great you could hook up another vacuum to it anyways, the heater and mechanics of the thing is the important part I guess.

Is the same clarke as the UK company that makes all the power tools and garage equipment?
 
The bed is 9" x 17"

There isn't a guage, unfortunateley. There are fuses for 'vac 1' & 'vac2' but no apparent selector switch. When I remove the vac 2 fuse it doesn't seem to affect anything.

On the back is a 3 pin apparent power out socket that is marked 'boost vac pump supply only via fuse vac 2'

Their is also what looks like some sort of hose socket.

Mysterious huh :lol

Though its an old model, the manufacturers still exist, so probably best to give them a ring.

I'm on holiday right now (we went to collect this beast on our way to my gf's sister's cottage), so I can't really try anything out till I get home, I'm just incredibly impatient
 
tango'd fett said:
Yeah nice buy ,how much did you get it for ,I been thinking of making one but if they are cheap to buy I may look around.
I imagine even if the suction is not great you could hook up another vacuum to it anyways, the heater and mechanics of the thing is the important part I guess.

Is the same clarke as the UK company that makes all the power tools and garage equipment?
Click to expand...

Cost me £150. I do know of another one of the same model that may still be avilable for a similar price, pm me if you're interested (and no, it's not this one :lol)

These are the manufacturers, btw http://www.crclarke.co.uk/
 
All the vac-forms I've used suck a pretty big volume of air. It sound like your machine has two pumps but is only running on one.
Best way to tell is run some plastic through it and see what it does.
 
The vacuum doesn't seem like much as it's evenly distributed across the table face, not just in one spot. Forming a piece is the only way to know if it's running weak.
 
Throw a part on there and lay a trash bag on it covering the whole bed.....turn on the pump it will suk it right down once there is no leak!!! :eek
 
TOSPHASER said:
Throw a part on there and lay a trash bag on it covering the whole bed.....turn on the pump it will suk it right down once there is no leak!!! :eek
Click to expand...

(y)thumbsup

Thanks for that tip! Tried it out, and we have total suckage :love
 
Hello have you sorted this problem yet. I know the answer to sorting out this machin'es little quirks. Drop me a mail and I'll help. All the best. Les
 
hi Birdie
i hope you solved your problem. i have a question. whats the mechanism of the table or bed for move to up and down? i want to build a vacuum former machine.
 
water24 said:
hi Birdie
i hope you solved your problem. i have a question. whats the mechanism of the table or bed for move to up and down? i want to build a vacuum former machine.
Click to expand...

Yup, working fine. Not sure how the mechanism works, as it's all enclosed. It sure is like working an old fruit machine handle, though..
 
Well, if you had a vacuum guage, you could check to see if you get 22-25 inches of Hg, which I've always seemed to make work. With a small pump, you may need to have a reservoir tank in line between the pump and the platen. It will get a larger volume of air to suck out from the underside of the hot plastic quickly, which is good, because once the hot plastic pulls down onto the top of the pattern (buck) it will cool quickly and you need to pull vacuum immediately. As far as your plastic, the thickness will depend on your frame's capability to clamp. Time and experimenting will tell, but cut the plastic big enough to reach beyond the frame so long as it doesn't get in the way of the mechanism. I would try .063 styrene, PETG(for clear parts) or thin ABS (for more durable parts) Vacuumformers love styrene which is great for model making. The ABS has to be sanded and cleaned with denatured alcohol before paint, however. The center of your plastic when heated may start to sag down a bit, but that's okay. The plastic is ready to pull down over the buck when the corners are soft enough to pull down and stretch over the edges of the platen seal frame. Have fun.
 
Oh, yeah, I forgot. If your platen is not grooved for air flow, your buck may seal of the vacuum port. You can put screen down on the platen or put the buck up on pennies. Just make sure your buck is made to take heat (painted things don't work well) and pressure because you'll be pressing on it with 14.7 psi when it's under vacuum.
 
Wesman said:
Oh, yeah, I forgot. If your platen is not grooved for air flow, your buck may seal of the vacuum port. You can put screen down on the platen or put the buck up on pennies. Just make sure your buck is made to take heat (painted things don't work well) and pressure because you'll be pressing on it with 14.7 psi when it's under vacuum.
Click to expand...

Now he tells me! :lol

Yeah, I didn't realise the mould was under so much pressure until the last couple of weeks' experimentation and a few collapsing masters :angel

I've been using 1mm HIPS, works pretty well until you try pulling something more than a couple of inches depth. Might try some thinner styrene to see ifI can up the ante.
 
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