To Build A Ski Press...

doughboyshredder · 02-12-2009, 09:24 PM

Too funny. I was just going to send you a pm. I am gonna post up a real thread about the whole process and the plan shortly, but here's a teaser.

I will be posting a full thread sometime in the next couple months, with more details including the first production run shapes with graphics, company name, etc...

This is probably the funnest project I have ever completed. The stoke of carving turns on something you built is unreal. And I gotta say, my boards kick some serious ass.

Watching ON3P has been motivational to say the least.

If this is something you want to do, fucking do it. Seriously. The resources available thanks to the net are incredible. Will it cost a bunch of money? Yeah, more than you thought. Will it be fun? Yeah, more than you thought.

**iggyskier** · 02-12-2009, 09:35 PM

Originally Posted by jondrums

Hey Iggy-
I don't think you should be using the sheer strength for the calculation! From your pictures, I think you want to use the tensile strength. But it turns out that the sheer strength of those bolts is about 75% of the tensile strength.

Haha well there ya go....gotta remember, I was a biology kid, so still picking up a lot of this stuff

**RaccoonFace** · 02-12-2009, 10:02 PM

[dickasshole] bull shit post, that is highlighted below but has no business being here at all. I'm sorry to all the people who read it, and I'm erasing it so it doesn't kill the momentum of the thread. I'm embarrassed and I sincerely apologize for it since it was everything that was not "community".[/dickasshole]

okbye

EDIT: I think this is pretty fucked. Sorry, shitty day and I'm snapping at everyone. This was uncalled for, inappropriate, and not constructive at all.

doughboyshredder · 02-12-2009, 10:23 PM

Originally Posted by RaccoonFace

RAD, 2 pages and I'm still on page 1. I didn't want to post in this thread, but I guess I need to now...

Those bolts are 1/2", but we discussed that via PMs.

I'm not even going to finish editing this for what I want. No, your calculations are not correct. You don't consider every damn bolt you have in the press. You consider the weakest points. If the weakest point is the place that has 8 bolts then you divide the force at that joint by those 8 bolts. By you reasoning airplanes are indestructible because they have a black box.

And you're not using the right values. You're using the shear values. You need to use the tensile values and those are not absolute.

Yea, by repeating "do it right" I was TOTALLY saying that Iggy should have welded it with a couple car batteries, jumper cables and a coat hanger. And even an amateur weld would help if there were only (2) 1/2" bolts at each of those top joint as I had initially thought.

I won't post here again, but feel free to build your next press out of tin foil and toilet paper rolls. I won't say anything.

okbye

Why are you being a fucking douche?

Seriously? If you want to help and be constructive, then you might want to adjust your attitude.

You do consider every bolt in the press for one specific reason. You have equal pressure. You are basically building a pressure vessel. When built correctly with pressure dispersing molds you should have an equal amount of pressure on each mounting point. If your pressure is unequal then you would have some bolts needing to take more force than others, but with the molds that most builders are using this is not the case.

Anyway, fuck it. where's your press dickbag?

**krp8128** · 02-12-2009, 10:34 PM

Man, I just finished my homework on for design of machine elements; the topic was bolt loading and static failures.

The amount of FAIL in this thread is astonishing.

iggy, your on the right track, without running numbers it looks to be way overbuilt. Keep doing what you've been doing.

**RaccoonFace** · 02-12-2009, 10:39 PM

Originally Posted by doughboyshredder

Why are you being a fucking douche?

Seriously? If you want to help and be constructive, then you might want to adjust your attitude.

You do consider every bolt in the press for one specific reason. You have equal pressure. You are basically building a pressure vessel. When built correctly with pressure dispersing molds you should have an equal amount of pressure on each mounting point. If your pressure is unequal then you would have some bolts needing to take more force than others, but with the molds that most builders are using this is not the case.

Anyway, fuck it. where's your press dickbag?

I edited my first post apologizing. Sorry. I had a crappy day and I am snapping at everyone. Not your fault. I'm not even making complete thoughts. I'll come back tomorrow.

okbye

doughboyshredder · 02-12-2009, 10:42 PM

I had the same day yesterday. is all good. hope you feel better tomorrow.

**iggyskier** · 02-12-2009, 10:52 PM

Originally Posted by RaccoonFace

I edited my first post apologizing. Sorry. I had a crappy day and I am snapping at everyone. Not your fault. I'm not even making complete thoughts. I'll come back tomorrow.

okbye

no worries man. shitty days happen. hope tomorrow is a better one.

**Garrett** · 02-12-2009, 10:57 PM

Originally Posted by RaccoonFace

I won't post here again, but feel free to build your next press out of tin foil and toilet paper rolls. I won't say anything.

okbye

Yeah, I'm thinking about building mine from hemp and recycled paper, actually. I think some of your comments about how a structure like this simply should be welded are a bit OTT. More than one way to do things right. Note that I'm not making any value judgments about this particular press, I was told there'd be no math at TGR. Back of envelope calcs are eyebrow raising for sure.

iggy, there are aspects of your design that raise concerns just at first glance. I think RF is wise to suggest you take a second look at this, and I'd go further to suggest you bring it to someone qualified to do the analysis. At the very least those are good suggestions for version 2.0 no matter how it differs. One of the things that concerns me is that a)it can be disassembled and moved ergo b) a well meaning person might crank on the wrench and add a lot of preload to those bolts.

**iggyskier** · 02-12-2009, 11:14 PM

Originally Posted by Garrett

iggy, there are aspects of your design that raise concerns just at first glance. I think RF is wise to suggest you take a second look at this, and I'd go further to suggest you bring it to someone qualified to do the analysis. At the very least those are good suggestions for version 2.0 no matter how it differs. One of the things that concerns me is that a)it can be disassembled and moved ergo b) a well meaning person might crank on the wrench and add a lot of preload to those bolts.

I was present every time it has been disassembled and reassembled, and definitely know not to crank super hard on the bolts. The person who know has it now was told that too, and I don't foresee him selling it anytime soon, but who knows.

As I said, I know it was not the most optimal design. I knew this even while building it. But I also had to build something within my own manufacturing capability and that is how it turned out. For something that was literally made start to finish alone by a kid who had never designed anything like it before, never used a drill press, or never taken a single engineering class, and was balancing school, a thesis, and anything even remotely enjoyable all at the same time, I think I fared pretty well.

And I will definitely have someone who knows more about this double check everything when I finally get around to building version 2.0. Or by then learn how to do it myself. Already learning the business side of everything, might as well pile on a little more.

doughboyshredder · 02-12-2009, 11:50 PM

fuck doublechecking. close the door and pump the shit up to 150psi. If it doesn't blow, then you're good to go at 75.

**iggyskier** · 02-12-2009, 11:59 PM

Originally Posted by doughboyshredder

fuck doublechecking. close the door and pump the shit up to 150psi. If it doesn't blow, then you're good to go at 75.

.....That must be one beefy door.

**yippeekiyayMF** · 02-13-2009, 12:10 AM

iggy,

thanks for all your info. i'm drunk and wasted from riding all day in our lovely tahoe storms, so when i get sober (probably around sunday) i'll re-read everything to get a better understanding of what the hell you were saying. my main take aways:

1) weld the bitch
2) over build
3) put it in a room, close the door, and crank it up to 150 PSI. if it holds, i am good to go at 75 PSI (i keed, i keed!)

**DJSapp** · 02-13-2009, 09:41 AM

Originally Posted by doughboyshredder

The connection to the legs is completely irrelevant. The press could be sitting on a kitchen table (if the table could support the weight).

The red press has been used by Happy Monkey snowboards many times and has absolutely zero issues.

DBS,

With all due respect, you took my comments about Happy Monkey's press incorrectly. I stated that it was a design issue. If they rotated the beam 90 degrees into the strong direction (the direction the top and bottom beams are running), they could have used a much lighter beam and saved on construction costs and press weight. That is not to say that they could not have built the press the way that they did with a larger beam, it just lends itself to bending, and they chose the worst possible solution (purely from a design standpoint). Now the construction reality of it was that they got a length of I beam and built the whole damn thing from it, and that was cheaper than sizing and ordering every part.

As far as igs black press, the connections to the legs are absolutely relevant BECAUSE THEY ARE DOUBLE BOLTED. This gives resistance to the moment imparted on the upper and lower beams as pressure is applied. The shear loading in these bolts is the first point of failure in the frame. It would actually be safer if one set of those bolts was removed so the top and bottom beams could rotate on the frame and put the bending stress where igs calculated it for, on the three stacked tubes on the end.

Raccoon--Chill winston. 1. I didn't realize you were a civil engineer. I keep track of my cohorts on the board. 2. Unless the compressor is running and tubes are inflating, if a press were to fail, the yielding of the steel would cause the press to open REDUCING the pressure applied to the mold, leaving a bent press or deformed bolts. No explosions, fireballs or shrapnel. Death is not happening here. 3. The eight 1/2" bolts holding the stacks of tubes together at end of the beam are good for 56,500 lbs. He's good.

krp8128--Here's a homework problem for you: Two 1/2" bolts (36ksi) are spaced 3" apart. What is the maximum moment that can be applied to the connection?

doughboyshredder · 02-13-2009, 09:48 AM

Honestly I didn't even look close at how the legs are attached, because in my experience it doesn't matter. If the pressure vessel (press frame) does not deflect there should be no added stress on those bolts. On my press the legs are pinned on with a bolt with no nut. Inflated I have zero deflection and could easily remove any one of the four legs bolts.

**DJSapp** · 02-13-2009, 10:06 AM

Originally Posted by doughboyshredder

Honestly I didn't even look close at how the legs are attached, because in my experience it doesn't matter. If the pressure vessel (press frame) does not deflect there should be no added stress on those bolts. On my press the legs are pinned on with a bolt with no nut. Inflated I have zero deflection and could easily remove any one of the four legs bolts.

DBS, just because you can't see the deflection doesn't mean that it is not happening. From your description, the reason it doesn't matter is that your legs and pressure vessel are allowed to freely rotate between each other and your pins are only holding the weight of the press. If you double bolt it, the legs are now resisting the rotation of the loaded pressure vessel by shearing the bolt connection (assuming the legs are secured to the ground).

**Garrett** · 02-13-2009, 10:49 AM

Originally Posted by Garrett

b) a well meaning person might crank on the wrench and add a lot of preload to those bolts.

That came out retarded, my apologies. A well meaning person might yield those bolts. You've got your shit together though, and I can't wait to see version 2.

iggy, I can relate quite a bit to your post about doing this with a bunch of other time commitments and without much experience with tools. Tools aren't usually rocket surgery, but it sure is nice to have someone around who can show you how to do things in the most efficient way. Been learning lessons the hard way with tools since I was 16, and I'm always looking for opportunities to learn them the easier ways...

Originally Posted by DJSapp

2. Unless the compressor is running and tubes are inflating,

Kind of an interesting point. I've sort of assumed that those hoses leak a bit and require regulated make up air, not sure if that is a valid assumption. I suppose this would suggest that for safety, the air supply/regulator line should be a soft connection with limited volume flow as opposed to a big thick hardline to a 60 gallon receiver.

**iggyskier** · 02-13-2009, 01:18 PM

Originally Posted by Garrett

Kind of an interesting point. I've sort of assumed that those hoses leak a bit and require regulated make up air, not sure if that is a valid assumption. I suppose this would suggest that for safety, the air supply/regulator line should be a soft connection with limited volume flow as opposed to a big thick hardline to a 60 gallon receiver.

I think all hoses leak a bit, but some a lot more than others. I think the two things people have a lot of trouble with are making good molds and sealing the hose.

A lot of people can get the ends correctly but have a lot of trouble with the connection to the air hose.

**DoWork** · 02-13-2009, 01:27 PM

Originally Posted by RaccoonFace

Not ripping, just dropping a bit of health advice so do whatever you want.

This press will work... But, safety is a big issue and it certainly isn't (read: is not) overbuilt as a chain is as strong as it's weakest link (I'll come back to this). At the very least it needs to be welded.... This is a simply supported structure and improperly supported at that. Before you go out and start drawing up plans for your press first you will need to analyze the structure. Once you start crunching numbers you will see that there is an increadible amount of energy being stored in that press at even "low" pressing pressures of 50psi (average pressing pressure is 70-80psi). PSI stands for Pounds per Square Inch, so calculate the area (in^2) of your table and MULTIPLY that by 50. That number is the number of pounds being supported by your joints on only one half of the structure... OK there are a bunch of bolts at the bottom (better). But only 2 for each joint at the top (remember the weak link comment)? You are just asking for it. All that force you calculated earlier is being applied in shear across those little bolts... NOT safe... Do it right, and don't do it until you can answer the questions about the structure yourself or at the very least understand the explanation given to you about it. Because this ain't monkey nuts, this is a real tool with the potential for catastrophic consequences. And, if you're going to do it, do it right.

[/EHS Rant]

Hey man, I am an ASME QC manager, calculator, welder and engineer. Figuring out this type of thing is what I do for a living. Dood, he's using 70psi. That's like blowing a fart at it. It is overbuilt, but that's how it should be. U should see the bed I built for myself... Nice job Iggy.

Originally Posted by iggyskier

Holy shit man- you need a TIG welder! I know, I know- I read the part about the $$ and the experience, but DAMN THATS ALOTTA BOLTS!

Originally Posted by iggyskier

A lot of it came down to that fact that I have 0 welding experience. I actually had 0 experience with basically everything. My building resume before starting this was small tiny skateboard quarter pipes in high school, and a pvc skiing rail.

So I definitely did not feel comfortable welding my first press, nor will I personally feel comfortable welding the second press. It will be professionally welding. Definitely not taking any chances. I actually am going to try and learn to do it when sam and I build some custom ski racks that I have drawn up.

Let me know if you want somebody who does this shit professionally to look at your drawings. The key here is DRAWINGS. If you can put it on paper, I can make it. I've been at this for ten years and work at a family shop where I have the keys and would do it off the books. Your press is sicktah, but I'm sure you've found things you'd like to have done differently.

Originally Posted by RaccoonFace

[dickasshole] bull shit post, that is highlighted below but has no business being here at all. I'm sorry to all the people who read it, and I'm erasing it so it doesn't kill the momentum of the thread. I'm embarrassed and I sincerely apologize for it since it was everything that was not "community".[/dickasshole]

okbye

EDIT: I think this is pretty fucked. Sorry, shitty day and I'm snapping at everyone. This was uncalled for, inappropriate, and not constructive at all.

Werd. Again, nice work Iggy. Let me know if you want it welded next time. You'll probably spend the same money you spent on nuts & bolts on shipping, but it'll be done to the nines with a TIG welder...

**BestofShow** · 02-13-2009, 01:56 PM

Saving this thread for down the line. Iggy Thanks for the details mang! Love the pic with the backyard full of skis.

**jondrums** · 02-13-2009, 03:08 PM

Originally Posted by doughboyshredder

fuck doublechecking. close the door and pump the shit up to 150psi. If it doesn't blow, then you're good to go at 75.

I'm nervously laughing because, a few years back I had a not very fun accident with a compressor based potato gun. I didn't let the PVC glue cure on a 4" pipe cap, and it blew off at 120psi - missing my head by a few feet, and making a hole in the door next to me!

**FrontRangeDrummer** · 02-13-2009, 05:04 PM

PM Mongo for some insight on this topic. He should be doing test runs on his second press by now.

(Mongo, are you reading this?!

)

doughboyshredder · 02-13-2009, 07:51 PM

Originally Posted by DoWork

Hey man, I am an ASME QC manager, calculator, welder and engineer. Figuring out this type of thing is what I do for a living. Dood, he's using 70psi. That's like blowing a fart at it. It is overbuilt, but that's how it should be. U should see the bed I built for myself... Nice job Iggy.

..

awesome!