New press - Mongo style !

ben_mtl · Post by **ben_mtl** » Tue Oct 06, 2009 10:58 am

Ok, here is some progress on my press (finally !)

I had really hard time finding a good CNC service to cut the ribs for my mold. Actually the one I ultimately worked with was not that good and had to make the parts twice, even the second set was not perfect but I was tired to wait and teach them how to use their CNC so I took the parts and I will make it work. It was a small skateboard company 2 kids started 2 years ago so I was patient but it's a PITA when you have to tell them not to cut in 1 pass over 3/4" MDF or when some parts are burnt because they didn't had to tool to plunge away from the final cut...

I also had some templates CNC cut, not perfect because of burn marks again but I will make it work with some sanding and car putty.

Anyway it keeps going for my press, my blankets are on their way, I have 2 PIDs, SSR should arrive soon, bladder is functionnal and I'm now working on the cat-track. I decided to go with an Aluminum cat-track as it's lighter, meaning it will "easilly" push the bladder against the top mold when not inflated. I'll use 3/4"x3/4" and 3/4"x1", 1/16 wall with round corners.
I heard people saying aluminum cat-tracks act like a big heat sink. With 2 blankets I don't think it's a very big deal but still I'm looking to eventually find a way to insulate the top blanket from the cat-track. I was thinking of some hard silicone-like rubber (maybe 1/8" thick) that I could fit between the heater and cat-track. How do you think it will affect my pressure distribution and do you think it will effectively insulate the heater ?

For the rest of my "ski-building experience" I have almost all the materials I ordered, I'm just missing the sublimated topsheets ! I will be able to make skis though as I also have some clear topsheet to try with colored fabrics and also want tto give a try with wood veneer as as topsheet !

Some pics will come as soon as I can go to my "shop" (friend's basement)... My mom's visiting so I don't work on my skis as much as I would usually do...

bobbyrobie · Post by **bobbyrobie** » Sat Oct 10, 2009 1:33 pm

the aluminum cat track works great for me. i sit the blanket on top of the cattrack keeps everything out of the way. heat transfers thru the aluminum quite well.

ben_mtl · Post by **ben_mtl** » Tue Oct 20, 2009 7:56 am

Well I went with an aluminum cat-track, I'll just add a layer of masonite between the top blanket and cat-track for insulation purpose.

Right now I'm working on a cassette system for the press. It's gonna be a very basic system : just 2 aluminum plates to sandwich my layup.
Basically as everything is adjustable on my press I will have my bottom blanket directly sitting on top of the mold (MDF) with nothing over it..
I will layup the skis on the bottom plate of my cassette, then put the top plate over the layup, then the top heating blanket, a piece of masonite and slide that into the cavity.
My cavity is small (to maximize the pressing area) so it's gonna be tight to fit the cassette that's why I'm going with a pre-formed cassette.
What aluminum thickness do you guys suggest for the cassette ? I found lots of different things on the forum but no real discussion about it. I went to visit a local snowboard manufacturer and he uses 1/8" so I went to my metal supplier and took some .100" they had in overstock.
The thing is it's pretty thick and I don't know how I'm gonna bend the tips and tail by myself... I'm wondering is 1/16" would be a better choice (so I can bend it myself, and save some money) but I'm concerned about the cattrack leaving marks on the top sheet. I'm probably worrying too much because the masonite should help a lot, especially as will only press @35-40 PSI !

So yeah I guess my question is : what would be a good thickness for a basic aluminum cassette ?

I'll take some pics of the press tonight, I just have not to forget my camera again !

Ben

redbull · Post by **redbull** » Tue Oct 20, 2009 2:34 pm

we use 1/16" aluminum sheets for our cassette. we then put two sheets of masonite board on top for insulation and protecton from the cat-track. we've seen no signs of cat-track indentation.

bobbyrobie · Post by **bobbyrobie** » Tue Oct 20, 2009 3:26 pm

im using .050 alum sheet and have pressed at over 85 psi without any indentation you should be fine.

sammer · Post by **sammer** » Tue Oct 20, 2009 3:42 pm

What about using your press to bend it?\
put it in your mold and put the air to it.
It would be worth a try.

sam

ben_mtl · Post by **ben_mtl** » Tue Oct 20, 2009 5:45 pm

Well, bending in the press directly will not be enough I guess as you usually have to over-bend so the metal matches the expected shape when it relaxes.
I'll give it a try though... just curious !

Here are some pics as for today at the shop :
General view of the press :

Tip block:

Tail block:

Bladder connection (thaks Headmonkey !):

pressure gauge 25$, valve 20$.... no way ! found this thing to inflate tires for 10$, modified it and it's just perfect !

PIDs and SSRs waiting for an enclosure and also for the blankets :

Busy workbench:

I'll try to change my .100" aluminum for 2 sheets of 1/16"... it's just gonna be easier !
Can't wait to receive the blankets and start pressing (right now the temperature in the shop is not enough for epoxy to cure...)

Any comments are welcome !

Ben

sammer · Post by **sammer** » Tue Oct 20, 2009 6:10 pm

WOW, ben your press looks awesome.
You've been busy!
Is your top mold made out of 2x6?

Can't wait to see the product.

sam

skidesmond · Post by **skidesmond** » Tue Oct 20, 2009 6:13 pm

Nice setup! I like the way you're supporting the cat track. Great idea! I'm going to try the same thing. I bought HD bungy chord and it works good but it doesn't pull up enough of the cat track at the same time. I'm going to thread some wire into my cat track so the bungy chord pulls up more of the cat track. My cat track was made from left over MDF that I had. It does the job but I like the aluminum better.

nick · Post by **nick** » Tue Oct 20, 2009 8:34 pm

is aluminum cat track really needed? Would just plain 1 inch steel work? Why does everyone use aluminum? Its a lot more expensive and its on the other side of the heat blankets so its not taking any heat away from the boards or skis anyways ryte?

doughboyshredder · Post by **doughboyshredder** » Tue Oct 20, 2009 11:26 pm

Nick, imo the only advantage of aluminum is weight reduction. Aluminum is also used for the purpose of cooling down electrical parts because it transfers heat away from the source so efficiently. Again, imo having an aluminum cat track above the top heat blanket without isolation can cause your top blanket to have to work harder to attain your set temp.
bobby, I like your process of having the blanket above the aluminum cat track, I think that is a better way of doing it for sure.

benmtl, your press looks great. I like how your braces swivel out of the way. I f cked mine up and I don't have enough room to swivel them out of the way. I didn't think about making the clearance until it was too late.

I don't think you should expect much relaxation in your final shape. Using such a well built press with dual heat blankets and controls with significant pressure, you should be golden.

Also, I think you might see that under full pressure your tip blocks might pivot some on that one bolt. Have you done a full pressure test yet?

ben_mtl · Post by **ben_mtl** » Wed Oct 21, 2009 3:44 am

Thanks for all the comments !

Sammer -> The top mold is 2x6 only, I tried to make those holes to save on weight but it's still pretty heavy. It's aslo pretty cheap though and I made it so I only have to change the ends to match my rockered tip&tail bottom molds.

Nick -> I hesitated a lot before going with Aluminum, originaly wanted to go with wood (Steel is ways too heavy IMO) but it would have been a bigger PITA to make it... As I said in a previous post I'll have a layer of masonite between the top blanket and the cat-track, it will act as an insulation and as pad to "protect" from indentation.
Aluminum is not that expensive, it ran me under 100 CAN$ for the whole cat-track (7 x 21ft length of 3/4" square, cut to 16in pieces !)... you then have to add the wire (a huge 3$) and spend an afternoon drilling and cleaning.

Dougboyshredder -> I only tested at 30 PSI for now, and had no retension system for the blocks.. it didn't seemed to move. The way the top mold is built, it creates a downwards force on the tip & tail blocks when the bladder inflates, that might help it not to move. If it moves though it can't go that far. I'll try to think about a better solution but for now I just want to have something functionnal so I can make a pair for this winter !

ben_mtl · Post by **ben_mtl** » Wed Nov 04, 2009 7:27 pm

Well, I tried to bend the 1/16" aluminum directly putting it in the press... it doesn't work ! It conforms to the mold (hardly) but relaxes as soon as you deflate the bladder... I have to find another way !
Maybe 1/16" is still too thick, don't know... but I'll make it work !

MontuckyMadman · Post by **MontuckyMadman** » Thu Nov 05, 2009 10:52 am

you have to anneal the AL to get it to soften. You are most likely using 5052 or some other very hard AL. The al sheet must be heated to 650 F to anneal the metal, then it will bend and dent easy.

You can torch soot the AL sheet with a acetylene torch on a reduction flame and then burn off the soot and that ill be about 650F.

ben_mtl · Post by **ben_mtl** » Thu Nov 05, 2009 11:50 am

I don't have the tools for that, my only torch is the propane one I use to melt P-Tex when I'm tuning my skis...
I was able to bend it over a large PVC pipe, not that accurate but it works and the press makes the rest when under pressure.
Tonight final touches to the cassette and a couple more tests on the press, tomorrow I go get the blankets... hopefully on saturday morning I'll be pressing my first pair of the season !

Then I'll take time to improve, but for now I just want my pair before the snow falls !

Will keep you posted !

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Ski Builders Forum

New press - Mongo style !