Geoff's (Mongo) New Press

[Mongo]

So I have the new press all done. It is a space frame, side loader with a cat track, adjustable top and bottom mold, 18"x80" 2500W each silicone heating blankets on the top and bottom of the ski material, and fully timer relay automated heating and pneumatic control system. I have been building it in the basement of one of the engineering buildings here at the University of Wisconsin, and keep forgetting my camera to take some pictures so those will come sometime this week. However, I just finished wiring and testing the electrical control system and it works great so I have some pictures of that:



Here is the front of the box. The switches are illuminated when the 120V line is plugged in. The red switch supplies power to the top and bottom blanket temperature controllers, as well as initially power the 2 pole timer relays. The green switch controls the start signal which closes the normally open timer relays and activates the timing cycle. I have the timers set up on One Shot mode so after the start signal is relayed, the timer relay closes for the time it was set then opens. The timers on the left side are control two N.O. mechanical relays that transfer power to the heating blankets (see pictures of the inside of the box). The timer on the right controls the pneumatics through the use of a 3-way solenoid valve that runs between the compressor, bladders, and the room for the exhaust.


Here is an overall picture of the inside of the box. More detail in the following two pictures.


Here is the inside of the box. Circuit terminals for 120 Volts up top, 220 Volt terminal in the middle left, 600 Volt 15 Amp mechanical relays with 120 Volt coil are the white things, Solid state relays are the teal colored guys. All of the relay control is through 120 Volt coils, and the 220 Volt is only used to power the heating blankets.


Here is the back side of the cover. This is how the automation stuff ended up being wired. Timer relays are set up as double pole operation so they break both legs of each electrical circuit for safety.

I am really happy with the way everything came out on my press. You will have to wait for the pictures to get a good feel for it, but it from the same school of thought as the press Kingswood Skis uses. With everything, including the compressor on the shelf under the press, it weighs under 500 lbs with a non ribbed mold width of 20" and 86" long. The overall press is 90" long and width 24"OD, 20"ID. It is pretty beefy with a minimum safety factor of 3.7. The only bitch was that I spent my entire spring break fabricating and welding. The welding paid off though as I have no bolts taking load, and I can break the press and wheeled cart down into 5 pieces and fit it all easily in the back of my 1992 Compact Nissan pickup (Had to do this at 1 am when taking it down to the do it yourself car was to cleat the oil and cutting fluid off of it, didn't realize how many homeless people in Madison sleep in the car wash bays on S. Park street, slightly sketchy when getting yelled at by them while they were breaking bottles). Regardless, pics to follow shortly, and if you have any questions about the electrical system please fire away. --Geoff

[RoboGeek]

very nice.. wanna wire my car?? hehe

[Mongo]

So a little over a year ago I finished a ski press and still haven't gotten to test it out yet. Between graduating from college May 2007, proceeding to get bounced around America by my job and living in hotels for 6.5 months, and finally buying a house 3 months ago things have been busy. The good news is that I now have my press in my garage/shop, my CNC router and dye sublimation setup is currently shipping, and I finally don't have to work in a shared basement. Anyway, here is the press I built. Hopefully it works well.

Here was the steel I initially bought to build the press. I ended up with about 6" of 2x2x0.125 left over so planning was good.


I welded all of the frame components, and the vertical stays on the sides are pinned through the welded brackets.


Here is a top down view after I finished the frame fabrication.


Here is me with my aqua welding jacket. I am 6'6" for reference.


Here is the final product as of April 25, 2007. I am going to change the top mold to make it adjustable to more aptly match the bottom molds versatility. The aluminum cassette and heating blankets are also not shown here. Well, the heating blankets from MEI are in the box next to the compressor.

[knightsofnii]

that looks awesome.
did you build the molds? they look almost identical to sbm adjustable mold.

let us know how it works and how the steel beams hold up under deformation, etc. because a nice lighter press would be great for us but not at the expense of deformation.

[G-man]

Very nice. Simplicity and efficiency at it's best.

G-man

[hugocacola]

that looks awesome.
did you build the molds? they look almost identical to sbm adjustable mold.

let us know how it works and how the steel beams hold up under deformation, etc. because a nice lighter press would be great for us but not at the expense of deformation.

Actualy in my case i had to move to a big press because pressure deform everything even the mdf mold, afterall, by my experience mdf mold doesent hang to much temperature and pressure at the same time... becarfull
its my advice

i was complaining by the weithg of my last press, dass. had built this one, and only 4 people can move it, slowly...

happy nice building

[knightsofnii]

yea we can only move ours in pieces, my guess is its over 2000 lbs.

[G-man]

Geoff,

Your press and my press are pretty similar in basic design, and I get no deflection at all with my press. The key to resisting deflection is the inclusion of the removable uprights along the length of the press. I keep seeing all of these massive presses being built from I-beams that weigh a ton (or two) and that don't really resist deflection all that well... greater mass doesn't always translate to greater stiffness. A lightweight well engineered press that is made from 2x2 square tube is stiffer, lighter, and less expensive. The main difference between your press and mine is that the 'floor' and 'ceiling' of my press run full length/full width 2x2 material. Your design is lighter and uses less material, but I'll be curious if you notice any deflection of your molds into the spaces between your top and bottom cross members. I think it's unlikely, but with a lot of heat and pressure, a little deflection might show up.

G-man

[knightsofnii]

i concur with g-man.

our beams deflect enough to spread out in the middle. And i'm probably going to brace them up somehow with some uprights. We already have bracing to keep the beams from spreading but i'm sure there's still some deflection.

[camhard]

ya, once you put even a couple or supports other than at the ends of your press, you dramatically reduce the force on each section and can use way less material. I had been planning on doing mine out of I-Beams and was dead-set on having one that could side-load. after a very long time, coming up with various designs, calculating and trying to justify an i-beam press, i finally made one out of 2x4 steel tube and flat bar. I can move the thing around in a small S10. I'll post pictures when I finish painting it and everything (Im sandblasting right now, which takes forever without a proper set-up or the time to do it). So I obviously can't comment on its durability, but I think it will last well (it is almost identical to the Kingswood press which seems to hold up to 200+ skis a year and has been in use for a few years).

A quick question if you don't mind: what kind of press do you use and how much did it cost for the metal alone?

Thanks.

[camhard]

oh ya... why did you do 2 PIDs? can those ones not handle multiple loads? i know a lot of them can do more than one blanket at different temps, but maybe not those ones. those are the ones that are everywhere on ebay right? do they work okay? I was a little leery about getting one for $35 from a company I'd never heard of.

[knightsofnii]

A quick question if you don't mind: what kind of press do you use and how much did it cost for the metal alone?

Thanks.

are you asking me?

my press is on my myspace page.

its an airbag press similar to everyone elses, except we have a 16" wide air bladder. dont ask me where it came from because I have not gotten an answer yet. I got it from Jeff at November Boards, and he used it to make cap boards and it worked quite well. We're making sammich boards and are going to do a few things differently, like cat track and cassettes, some other custom things.

we have six different molds ranging from 125 to 170something, so we can make a pair of park skis too probably :).
the small mold will come in handy because i just designed a sick 130 mini park board .

[camhard]

I was just putting the question out to anyone.

[G-man]

camhard,

I'm just getting ready to install a top heater in my press (in addition to the existing bottom unit), and I also plan to use a separate PID for the top heater. You are correct that about any PID controller can handle multiple heaters (amount of load is primarily dependent on relay rating). However, many PID units have temperature sensing input from only one source. The output control of the PID usually controls a relay device. The current load of controlled devices (number of heaters you can hook up) is limited by the current rating of the relay. If you run more than one heater from one PID controller (via the relay), you can only control the current supplied to all of the heaters based on a temperature reading from one single location. If if you were to run two identical heaters that sink the same amount of heat (based on the mass they are in contact with), then you could probably run two heaters from one PID and the heaters would supply about the same amount of heat to the mass to be heated. So, to make a long story short, it's pretty tough to accurately control current input (heat output) to multiple heaters without using multiple PID controllers that can actually sense temperature readings at multiple heat zones. PID's that can control multiple heaters are more expensive and more difficult to program. I haven't shopped around for PIDs lately, but I don't recall seeing many multiple control units when I was shopping.

The $35ish PIDs sold on ebay have been quite reliable for me so far. You just have to make sure that you get some sort of users manual with them... they're a bit tricky to program until you get the hang of how they work, and attempting to program without some sort of programing guide is very tough... at least for me.

G-man

[Mongo]

With regard to press deflection, there is no real measurable deflection across the long axis of the press. I matched the vertical stays specific to the brackets they pin into, so the fit is nice and tight so there is no slop from one stay to the next. I have run the pressure up to 100 psi, keeping in mind the cat track width and force distribution is 20" across, and have not seen any deflection into the dead spaces on the top and bottom by my molds either. I do have a piece of 1/2" ply above and below the top and bottom molds to help distribute force more evenly.

With regard to the electronics, I wanted to use 2 PID controllers to have greater control over what I wanted the top and bottom blanket temperatures to be. I want to see if different heating patterns can give predictable camber results from a single mold. That is to say, I want to see if I can get away with one mold and predictably vary ski camber by heat treatment.

On some new stuff, my 4' x 8' shopbot cnc router is on its way and will be here in 4 weeks. Dye sublimation setup has also been ordered. I have all materials to manufacture 35 pairs of skis arriving from their separate suppliers so hopefully I can get a little more active in the board this upcoming summer season. Some things I am really interested in working out is expanding on a flex predictability model I made from testing skis in measurements lab, working out dye sub compatibilities, and rapid prototyping a ton of different skis! Overall I am pretty psyched to try my hand at a new direction in design and get some people who don't live in North Dakota ski testing for me next winter.