Need some help with forklifts

Hello Cd,

I was wondering what material did you use to pull your forklift mast up and down. Last year we used fishing line and that did not work very well. Can you please put a link to your material and we were thinking of using cable? Also could you include pics of your system.

Thanks,

Rc

We didn’t use a forklift but our feather was driven by steel cable which might be an option for you. Word of warning if it has plastic coating on it that will peel off LONG before the cable fails so you may want to strip it off in the part you use to secure it down. We were useless an entire match due to striping that plastic off and not being able to raise our elevator which covered our shooter.

We used 3/32" diameter uncoated steel cable for all stages of our lift. We initially worked with 150 lbs. test fishing line, but it stretched far too much to be useful.

228 has used 25 pitch roller chain on our 2007 elevator and Spectra cable on our 2005 elevator.

I’d also like to work on a design that uses timing belts sometime.

Do you have links of where I can buy these products, thanks guys for your help.

Two #25 roller chains for first segment.

Two 1/16" steel cables from ACE Hardware for the carriage segment. We never broke or stretched these cheap cables. They had springs attached to one end that allowed them to stretch when the carriage reached the top.

Can’t beat ACE! :smiley:

Picture.

Look through “the usual sources”: McMaster-Carr, MSC Direct, Grainger, or Small Parts.

25 pitch roller chain is easy to purchase, although Spectra (sometimes called Dyneema) cable is a bit harder to find. I prefer Spectra cable to steel cable; 7/64" Spectra cord has an ultimate breaking strength of above 1,000 pounds, it doesn’t stretch any appreciable amount, and it’s a lot lighter than steel cable at only 0.3 lbs per 100 feet. The only real downside is that it costs $1 per foot.

I like spectra for a lot of things because it’s so light, flexible, and relatively cheap, but we’ve discovered that it’s pretty annoying for telescoping lifts and such. Spectra has pretty severe creep, which means that it slowly, permanently stretches when it’s under load, especially a high load. So any lines that you pretension are inevitably going to get loose as the season progresses. I’ve since come to appreciate Vectran. It has a lower modulus than spectra, so it will stretch more under load, but it’s approximately a heck of a lot more flexible and lighter than steel cable of similar breaking strength, and it has zero creep. Spectra is best purchased from kite shops:
A Wind of Change
Windstar Kites
Vectran lines are available at sailing shops:
Mauri Pro Sailing

EDIT:
Art, you’re being taken advantage of if you’re paying $1 a foot for spectra if you like it that much. See my links above. Buying in bulk should get you spectra for half that much.

1251 had a lift system this year we used 1/16in thick steel cable and UHMW plastic pulleys with an 1/8th in grove to life our elevator up. The motors were the small and big banebot if my memory serves me corretly and don’t quote me on this rs 440 and 550 combined in a custom gearbox. The material for the actual elevator was 2*1 1/8in wall box alumnium. 254/968 has a spool thats really cool its like spring tensioned. I’m sure Cory, Sanddrag or Travis can tell you more about it and where to get them. Some other notes about elevators don’t put all the pneumatic lines thru igus on one side if you have more then 4 lines it doesn’t work well and run as much line as you can inside then out of the elevator to keep everything out of the way. This will save you alot of dispair and grief during the competiton season.

http://www.chiefdelphi.com/forums/showthread.php?t=64896&highlight=1251+robot+08

Hope that helps,

-Drew

Where did you get the cable from??? I’ll have to ask Cory or if he could explain it here with some pics, that would be greatly appreciated.

Thanks for those links.

I was never the person directly in charge of purchasing spectra cable when we’ve worked with it, and that’s the price I was told. Maybe because we only bought enough for our elevator and a spare, or maybe because we should have shopped around some more. Whatever the case was, I’ll be sure to keep my eyes open in the future when 190/228 purchase some.

I’d advise against spectra cable. Yes it is strong, but it doesn’t take shock very well at all.

This past year we used 1/8" nylon rope on ours. I was skeptical about how well it would work out, but thankfully it held up and only began to fray recently. In 2005 we used steel cable to drive our parallel arm.

team 675 used #25 chain and # 15 chain to lift our two stage lift

I don’t remember the exact name of what we used, but I know it’s some sailboat rope. I think like 1/8". We never had any problems with it. It didn’t stretch much either. If you have a local West Marine, that’s where we bought ours from. I tried finding it on their website, but I didn’t find it.

This is probably pretty close: http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/4215/377%20710%201908/0/Running%20Rigging/Primary%20Search/mode%20matchallpartial/0/0?N=377%20710%201908&Ne=0&Ntt=Running%20Rigging&Ntx=mode%20matchallpartial&page=CategoryDisplayLevel1&isLTokenURL=true&storeNum=2&subdeptNum=490&classNum=11452

Our’s is blue though, so it may be a different brand. Look at the breaking strength… 530lbs. That’s a lot of trackballs.

We used size 25 chain to drive our first stage, with spectra pulling the second up and down.

We used bungee cord to counterbalance the stages the motors didn’t have to lift the weight of the them.

One thing to note about using any time of spectra or other line - tieing a knot in it will reduce the strength on the order of 40%. So, for instance, if you had a piece of line with a breaking strength of 500 pounds, and tied a knot in it, the break strength at the point of the knot will only be around 250 pounds. That sounds like a lot, but we managed to break a piece of spectra line with a break strength of over 1000 pounds when we were lifting a trackball and then got hit from the side by another robot (hard). If you can find a local rigger or a West Marine, they can splice the rope for you and eliminate the sharp bends that you’ll create by tieing a knot. Or if you can “wrap” the spectra around whatever you’re tieing it to several times then tie a couple half hitches, you’ll eliminate that problem.

Shock loads are killer. Forces in a 10 mph collision have been measured at over 8 g’s in the auto industry. We go a lot faster than that.

Another thing to note is that most spectra will not have a cover on it like your standard “West Marine” line, and that it is very susceptible to chafe. Vectran less so but you will certainly pay through the nose for vectran or any other high-tech line.

222 has used 1/8" steel cable, 3/32" steel cable, 1/8" spectra cable, #25 chain and timing belts for extension devices. Out of everything we used I would say that I liked the chain and timing belt the best. You can’t get much simpler. We used steel cable for years and that worked out well for us but many of us got tired of the frays on the steel cable making us bleed. So we eventually moved onto Spectra cable. I will utter the woes of the spectra cable creep. It gets very annoying. #25 chain is bullet proof for most FIRST lifts and can be as simple as a sprocket on a motor and a sprocket on a fixed member and an attachment block to the piece you want to extend. Timing belts can be used the same way the chain can, they are lighter and if tensioned correctly almost as strong. We used the timing belts for extension in our arm this year and we were impressed with how smooth the motion was. As far as chains and timing belts go your can find tons of sources. The timing belt and pulleys we used were supplied in the kit this year and they held up great! As far as a source for cables or other types of rope, here’s a source I found that’s got a little bit of everything.http://www.us-rope-cable.com/?gclid=CJflpoXquY8CFQWAHgodgjYNWw

Hope this helps

We’ve used 1/4" nylon rope before. It just happened to fit the groove in those ball-bearing sliding door rollers that are available at Home Depot: http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&langId=-1&catalogId=10053&productId=100200036

One team used some 1" wide nylon web strap, like you find on tie-down straps. That was nice because it would feed nicely on and off the winch mechanism. Plastic strapping used for shipping might work.

We used it this year and it was good stuff once:

You have a friendly attachment as it can easily be cut by sharp edges
You have learned how to tie a good knot. Knots can reduced the strength rating by as much as 75%. Here is 1 link:
http://www.caves.org/section/vertical/nh/50/knotrope.html

You keep it relatively clean. (grease and filings can hinder flexibility and lengevity.
You have a good tensioner system.

These are a lot of provotionals, but once these are set, it works great.

Anecdote:
We bought our original stuff from Small Parts for $100 for 100 feet. We had to re-weld a part on our robot right before ship day and it partially fired one of our strings. It broke at our first regional in Chicago. We bought 300 feet in Chicago for $75. The purchase trasaction and pick was an interesting story in itself.

If you go with cable, make sure you have a good crimper. I don’t mean a vise, I mean a cable crimper. 330 used to do lifts a lot (then discovered the joys of a single-joint arm), and when they did, they used cable, powered the lift both ways, and used a crimper used for aircraft cables. I don’t think we broke any cable or crimps, though we once bent a lift by powering down while it was all the way down. Yes, bent.