This weekend I will be making a ski press. It will be welded from 10hx10w 1/2 I -beam with 14h x 8w 1/2 middle. Design will be similar to HeadMonkey, but stock up one above the other so only 3 beams will be used. Do I have to worry about deflection on this design?
cavity dimentions wight 8" /10" hight 14" length 95"
Frankly I'm a bit concerned about 8" wigth, is it wide enough? I have 8" flat firehose and for 160 mm max skis?
At this point when nothing is cut yet I appreciate all suggestions.
someone locally selling old Montana Belt grinder with two belts, supposably in working conditions. Will see/test it on Thursday, need some advise what to look for. of course right now I don't really need it now, but for the price I will keep it for the future
I can only cut once
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The problem I see with this design is you basically need to do twice the work, so two bottom moulds, two top mounds, two cat tracks, 4 heat blankets if heat is used etc. You need to do two cassettes rather than one when doing the layup, and you risk slight differences in the moulds. You should ask yourself if it's really worth it to save 1 length of I beam; if I were you I'd either commit to doing one ski at a time and just make a single cavity press, or buy the extra material and do a two wide press.
As for the design itself, the centre beam would be in compression and assuming both cavities are being used at the same time, would not deflect noticeably as the forces should cancel each other out. The top and bottom beams will be subject to deflection. According to http://www.roymech.co.uk/Useful_Tables/ ... _prop.html your beams are at least 73kg/m (assuming they are the same as UK standard size) so I couldn't see deflection being a major issue with this press.
Bear in mind it will also be very top heavy so you will need a way to keep it upright. My press is built out of lighter steel than yours, and uses two beams wide and if I wanted I could push it over by hand by rocking it back and forth a couple times. With the height of yours it could easily become a death trap. It's doable, of course, but I'd look at fixing it in place rather than putting on wheels.
As for the design itself, the centre beam would be in compression and assuming both cavities are being used at the same time, would not deflect noticeably as the forces should cancel each other out. The top and bottom beams will be subject to deflection. According to http://www.roymech.co.uk/Useful_Tables/ ... _prop.html your beams are at least 73kg/m (assuming they are the same as UK standard size) so I couldn't see deflection being a major issue with this press.
Bear in mind it will also be very top heavy so you will need a way to keep it upright. My press is built out of lighter steel than yours, and uses two beams wide and if I wanted I could push it over by hand by rocking it back and forth a couple times. With the height of yours it could easily become a death trap. It's doable, of course, but I'd look at fixing it in place rather than putting on wheels.
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MadRussian
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to my understanding 2 molds 8" wide equals 1 which 16" wide should use same amount material.So for build and lay-up prospective I didn't so it as a problem
Currently no plans about heat blankets, possibly forced air space heater where narrower press should heats up faster and evenly.
risk slight differences in the moulds???????? ===>Can you explain
Bear in mind it will also be very top heavy===>how about 3' wide base underneath so wheels will be much wider? also 14" beam can be used on the bottom for counterweight.
Currently no plans about heat blankets, possibly forced air space heater where narrower press should heats up faster and evenly.
risk slight differences in the moulds???????? ===>Can you explain
Bear in mind it will also be very top heavy===>how about 3' wide base underneath so wheels will be much wider? also 14" beam can be used on the bottom for counterweight.
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MadRussian
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here old ski press with similar design. It also top heavy probably more so compare to my design. Look in the picture this press have even smaller footprint as I thought should be to its height.
my press will be about 5' high with legs 4' wide with additional bracing if needed.
risk slight differences in the moulds===>if I cannot make 2 IDENTICAL moulds I shouldn't do it at all.
My plan to make removable bottom mould for layup and smaller lighter mould is a plus.
my press will be about 5' high with legs 4' wide with additional bracing if needed.
risk slight differences in the moulds===>if I cannot make 2 IDENTICAL moulds I shouldn't do it at all.
My plan to make removable bottom mould for layup and smaller lighter mould is a plus.
Last edited by MadRussian on Thu Oct 07, 2010 2:30 am, edited 2 times in total.
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MadRussian
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MadRussian
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No I'm not planning to press one ski at a time, of course 2 are only going to put them one above another instead of side-by-side.Richuk wrote:Are you intending to use a cat-track? If so, is this a point where your concerns regarding deflection appear again?
Not sure pressing one ski at a time is a good way to go - its very time consuming and you will invariably get different results.
Good luck!
yes I will be using cat-tracks, possibly one above and one below the skies, made from hardwood.
With the size of the beams, I am using, there shouldn't be any deflection.
My original questions were about:
1) What do you thing of a three beam design?
2) One of my beams is 14 inches high and only eight inches wide, while the others are 10x10. Is 8" wide enough?
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doughboyshredder
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MadRussian
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The press in the photo was the one I was going to do until I came across two pieces of box section - it was good enough for dynastar.
I think - and this is me - you are saying that you are creating a double decked press and if so and you are following Head Monkey, then you will be using the I beam to create the cavity at the end.
Three beam press - creative, particularly if you are short on space. I wouldn't make it the same height as shown in the photo and would think about bolting it to the wall.
Logically, so not having done any calculations, I would put the 14" beam in the middle. I suspect that deflection along the cavity is nominal, but assuming I am wrong, then putting the I beam used to create the cavity at 90 degrees will help you manage the stress more safely. I would prioritise safety over a nominal deflection suffered by the bottom beam.
Eight inches will be wide enough? Yes, its bigger than the base you are thinking of pressing. Are you intending to reinforce as per the photo?
One final thought - I would recommend a relief valve. As you appreciate, a steel press will continue to take the pressure until something goes bang.
I think - and this is me - you are saying that you are creating a double decked press and if so and you are following Head Monkey, then you will be using the I beam to create the cavity at the end.
Three beam press - creative, particularly if you are short on space. I wouldn't make it the same height as shown in the photo and would think about bolting it to the wall.
Logically, so not having done any calculations, I would put the 14" beam in the middle. I suspect that deflection along the cavity is nominal, but assuming I am wrong, then putting the I beam used to create the cavity at 90 degrees will help you manage the stress more safely. I would prioritise safety over a nominal deflection suffered by the bottom beam.
Eight inches will be wide enough? Yes, its bigger than the base you are thinking of pressing. Are you intending to reinforce as per the photo?
One final thought - I would recommend a relief valve. As you appreciate, a steel press will continue to take the pressure until something goes bang.
Hi MadRussian,
In an ideal world, one ski on top of the other should press and work out exactly the same, however I don't think this would be the case often.
If you ever move to using heat, you need the temperatures to be exactly the same on both skis or you can get variations in camber, which includes ramp up time. Temp controllers simply do not control heat this well, there will be differences in the rate at which each level conducts heat. This also means evenly distributed pressure, as pressure creates heat. It will be very difficult to get your cat track pressing identically on both the top and bottom mould. You have to load both skis in perfectly rather than just one mould.
It also gets messy with layup having two separate mould skins etc. Gives you less flexibility if you ever want to build something a bit different, like a mono ski or snowboard.
What is your aim with this press? Cost saving or space saving? If cost, then I would really strongly recommend against it, spend the extra $150 odd for a wide press. If you decide to move to heated pressing in the future you'll make that money back more than twice over with the savings on blankets, controllers etc.
If space, then it may be worthwhile.
To disagree with Richuk slightly (and having done no calculations myself either), I don't think it's necessary to put the 14" high beam as the centre for dividing the cavities. I beams are ridiculously strong in compression, so when operating both presses the 10" should be more than adequate. When only operating one, the centre beam is still reinforced on both sides rather than just one side, so you should see less deflection. If using it as one of the long beams anywhere, I'd be inclined to use it on the top the most, and put wheels/supports in the centre of the bottom beam.
Relief valve is always a good idea.
In an ideal world, one ski on top of the other should press and work out exactly the same, however I don't think this would be the case often.
If you ever move to using heat, you need the temperatures to be exactly the same on both skis or you can get variations in camber, which includes ramp up time. Temp controllers simply do not control heat this well, there will be differences in the rate at which each level conducts heat. This also means evenly distributed pressure, as pressure creates heat. It will be very difficult to get your cat track pressing identically on both the top and bottom mould. You have to load both skis in perfectly rather than just one mould.
It also gets messy with layup having two separate mould skins etc. Gives you less flexibility if you ever want to build something a bit different, like a mono ski or snowboard.
What is your aim with this press? Cost saving or space saving? If cost, then I would really strongly recommend against it, spend the extra $150 odd for a wide press. If you decide to move to heated pressing in the future you'll make that money back more than twice over with the savings on blankets, controllers etc.
If space, then it may be worthwhile.
To disagree with Richuk slightly (and having done no calculations myself either), I don't think it's necessary to put the 14" high beam as the centre for dividing the cavities. I beams are ridiculously strong in compression, so when operating both presses the 10" should be more than adequate. When only operating one, the centre beam is still reinforced on both sides rather than just one side, so you should see less deflection. If using it as one of the long beams anywhere, I'd be inclined to use it on the top the most, and put wheels/supports in the centre of the bottom beam.
Relief valve is always a good idea.
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doughboyshredder
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Wide enough for both skis to be pressed under the same mold.MadRussian wrote:thanks for the response. Could you explain why its a bad idea?doughboyshredder wrote:bad idea, imo.
Build it right. Wide enough for both skis to be pressed under the same mold.
not pressing under the same mold WILL give you differences between the skis.
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MadRussian
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I am doing 3 beams design for space saving and availability.I think my fabricator don't have anymore 1/2" beams. may be 1 but this beam 20x6 or 8 I don't remember.
I have no plans to add blankets. Instead going to make insulated box with forced hot air and thermostat. In this press design hot air should be more evenly distributed because press is narrow.
following Head Monkey, then you will be using the I beam to create the cavity at the end. ===> yes
I wouldn't make it the same height as shown in the photo and would think about bolting it to the wall. ===>shown in the photo probably was bolted to the floor at one point. totals high approximately 55 to 60 inches with legs 50" wide. Safety wise should be fine as I was told by several fabricators. Press will be on wheels
It also gets messy with layup having two separate mould skins etc.==> I was thinking about removable bottom mould to do layup and separate table for preparation.
Gives you less flexibility if you ever want to build something a bit different, like a mono ski or snowboard. ===>no
If space, then it may be worthwhile. ===> my garage is only 1.5 car wide with a lot of stuff in it.
looking at it from different prospective from materials available:
press can be made from 2 20". beams and 2 10" beams. Most likely this is overkill.
how about 2 10" beams and 1" thick steel on top/bottom of to make it double wide
I have no plans to add blankets. Instead going to make insulated box with forced hot air and thermostat. In this press design hot air should be more evenly distributed because press is narrow.
following Head Monkey, then you will be using the I beam to create the cavity at the end. ===> yes
I wouldn't make it the same height as shown in the photo and would think about bolting it to the wall. ===>shown in the photo probably was bolted to the floor at one point. totals high approximately 55 to 60 inches with legs 50" wide. Safety wise should be fine as I was told by several fabricators. Press will be on wheels
It also gets messy with layup having two separate mould skins etc.==> I was thinking about removable bottom mould to do layup and separate table for preparation.
Gives you less flexibility if you ever want to build something a bit different, like a mono ski or snowboard. ===>no
If space, then it may be worthwhile. ===> my garage is only 1.5 car wide with a lot of stuff in it.
looking at it from different prospective from materials available:
press can be made from 2 20". beams and 2 10" beams. Most likely this is overkill.
how about 2 10" beams and 1" thick steel on top/bottom of to make it double wide
"how about 2 10" beams and 1" thick steel on top/bottom of to make it double wide" - you'd be asking the 10" beam to do twice the work.
Space heater sounds a bit random imho. Have you thought about underfloor heaters? I have only been able to set up with room for just one ski at a time, which means I need to focus on the same pressure and temp. Just a thought.
Space heater sounds a bit random imho. Have you thought about underfloor heaters? I have only been able to set up with room for just one ski at a time, which means I need to focus on the same pressure and temp. Just a thought.