my press

sir.orange · Post by **sir.orange** » Mon Oct 18, 2010 7:10 am

hey,
as i found some remainding i-beams in a metal factory, im finally going to construct a pneumatic press.
it s a couple of "HEA 160" beams, i dont know if you can deal with this code. check out the attachment there s more information.

please check the press and dimensions according to stability against deflection, amount of space for pressing snowboards and skis.will the gap (8cm) in the bottom be a problem?

all connections will be welded

ruudsjoukes · Post by **ruudsjoukes** » Mon Oct 18, 2010 1:35 pm

The gab will be a problem since you won't be able to transfer energy in that space.

As well you don't want to put the Lowest I beam on it's side, it will deflect the upper I beam in the middle. You can just leave that one out. Like you did with the upper one.

I'd rather mount 3 I beams next to each other to close the gap.
This is just based on engineer technical deflection and stiffness. Hope it helps.

PS. Your outside dim could be 200cm since that's all you need. Will save you on costs and materials. You can put your mold through at the sidebeams isnt it

EricW · Post by **EricW** » Mon Oct 18, 2010 2:46 pm

Yeah, that 9cm gap will just act like a sieve and turn your form into mechanically separated chicken.

sir.orange · Post by **sir.orange** » Tue Oct 19, 2010 5:32 am

ok thanks, i ve fixed that gap.

will there also be the need of some ribs, like most people do with their presses made out of rectangular tubes?
just from your experience: what deflection may i consider with this beam construction (the one below)? will be 1mm or 1cm? and is it negligible or not?

so, this one might be better

ruudsjoukes · Post by **ruudsjoukes** » Tue Oct 19, 2010 6:48 am

I could do the calculation for you if you want to.

Will take me after work so will be tonight.

guess this works at least. What materials are the beams made off?

ruudsjoukes · Post by **ruudsjoukes** » Tue Oct 19, 2010 6:48 am

I could do the calculation for you if you want to.

Will take me after work so will be tonight.

guess this works at least. What materials are the beams made off?

sir.orange · Post by **sir.orange** » Tue Oct 19, 2010 8:44 am

ruudsjoukes wrote:I could do the calculation for you if you want to.

Will take me after work so will be tonight.

guess this works at least. What materials are the beams made off?

that would be awesome!!

it s steel i think S235JR or S355J2 (before 2006: St-37)
i don t know if this is the international code, but it s the "normal" steel, beams are made of

ruudsjoukes · Post by **ruudsjoukes** » Wed Oct 20, 2010 10:00 am

To share with everyone the data:

When putting 50psi on a HEA 160 steel 37-2 you will get a deflection on a length of 2 meters of 1,245mm maximum.

This is on the 'high and safe' side.
If you put the beams that hold the 3 next to each other, about 300mm to the inside instead of at the end of the beams, you will get a def. of 0.355mm maximum!

Hope it helps somehow.
Cheers!

sir.orange · Post by **sir.orange** » Mon Feb 21, 2011 8:12 am

hi there, i d like to share my newest problem:

after couples of hours the press is finaly build. last week i was running a test run with a first laminate of skis, but the result sucked...
in the tip and tail section of my mould is not even the pressure of 45 psi i pressed with...i recognized it checking the laminate: the area, where the wood core comes to 1,5mm core and hits the abs- tipspacer was a gap of 2mm filled with resin. the gap was between core and topsheet with...
in the flat section of the ski i have pretty good transfer of the pressure.

cat track: rectangular 20mm aluminium
hoses: 3 fire hoses, inflated 102mm diameter

the moulds: the negative mould is shaped one piece out of 11 38mm mdf boards, glued together. the positive mould is fitting exactly into the negative mould, its the rest out of the cnc mill...so: the distance of the two mould parts differs.(check the picture) in the camber area(flat area) its something like 8-9cm. in the rounded parts of tip and tail its maybe 2cm less. might this be the problem?

during the curing in teh press, the laminate is between 2 stainless steel metal sheets, each 1mm thick. the are not 100% fitting to the mould i fix this next time before pressing again.
but still the test runs without any sheets of boards or metals, only cat track and moulds i could move the cat track parts in the tip/tail area. all aluminium tubes were aligned correctly

Brazen · Post by **Brazen** » Mon Feb 21, 2011 8:21 am

I had run into the same problem with my press and solved it by shortening the top mold ends...if you look at yours, there's less of a gap for the hose to expand into right in the area you're having the problem. Also, shorten your cattrack, the pieces on the ends of the tip-block are actually pulling it up in the tip radius. That's my 2 cents. And, nice press!!

ben_mtl · Post by **ben_mtl** » Mon Feb 21, 2011 8:36 am

Hard to tell from the pics but tip mold radius might also be a bit too small. I found on my press that in order for the hose to conform to the mold WITH PRESSURE the radius has to be more than 200mm... I fixed my minimum @250mm for all new molds.
Too much space between the top mold and bottom mold could also be a problem... it looks OK though but the tighter the cavity, the more pressure area !

ruudsjoukes · Post by **ruudsjoukes** » Mon Feb 21, 2011 9:06 am

Looking at the design I would say; make the gap between your top mold and your bottom mold at the tips smaller. This will reduce the area which has to be filled with air along comes pressure.

Removing the elastic cords when pressing or reducing them to 1-2 may also help a bit..

My thoughts..

doughboyshredder · Post by **doughboyshredder** » Mon Feb 21, 2011 10:20 am

That's one of the reasons I press at 80 psi.

It takes a lot of pressure to force a steep radius. Partially because of how the bladders inflate evenly.

ON3P solved their problem with this phenomenon by adding pneumatic rams at the radius point. When I worked in production we did the same thing. A lot of professional presses do the same thing.

Richuk · Post by **Richuk** » Mon Feb 21, 2011 12:06 pm

Brazen wrote:I had run into the same problem with my press and solved it by shortening the top mold ends...if you look at yours, there's less of a gap for the hose to expand into right in the area you're having the problem.

I agree with this and I would reduce the gap between the upper and lower mould. This will give you a greater surface area under press from the hose and not the track.

I don't agree it takes high pressure to force a radius - sorry DBS. You just need to take a minute to look at what areas of the press pressurise first and put a slip layer in. I was using teflon coated baking sheets, worked like a charm.

Good luck when you press!

sir.orange · Post by **sir.orange** » Mon Feb 21, 2011 1:14 pm

thanks to all of you for your ideas, i still have some questions.
maybe a mixture of all your suggestions may help. looking forward to the results that may occur

Brazen wrote: Also, shorten your cattrack, the pieces on the ends of the tip-block are actually pulling it up in the tip radius. That's my 2 cents. And, nice press!!

you mean the track-parts that are overhanging? why pulling it up, the cable is balanced without any tension..!?

the smallest radius of the tips is something around 250-260mm....

doughboyshredder wrote: ON3P solved their problem with this phenomenon by adding pneumatic rams at the radius point. When I worked in production we did the same thing. A lot of professional presses do the same thing.

...interesting, how many aluminium tubes are forced by 2 rams, just ONE??

Richuk wrote: I agree with this and I would reduce the gap between the upper and lower mould. This will give you a greater surface area under press from the hose and not the track.

I don't agree it takes high pressure to force a radius - sorry DBS. You just need to take a minute to look at what areas of the press pressurise first and put a slip layer in. I was using teflon coated baking sheets, worked like a charm.

Good luck when you press!

didnt got that exactly...teflon coated baking sheet. you mean paper, coated with teflon? where to put it first, what happens then exactly?

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