Back in Feb when I started planning my OX build I ordered some Gates GT3-3mm pitch timing belt, they finally arrived. I am opting to use this belt in an effort to minimise belt stretch especially since I'm using 1500mm rails for my y-axis. Please don't interpret this statement as saying standard GT2 belt is substandard for the task, just that the GT3 "should be better". I found this chart online comparing HDT, GT2 and GT3 belt. Because of the long delivery time I decided to order a few extra belts, if you'd like some send me a message. They are supplied as 1692mm closed loop belts, 6mm wide. They work with GT2 pulleys.
I'm confused Anthony (easily done!) The belt you showed is, according to gates, 15mm wide. So either you used a stock picture and the belt you are actually using is GT3 1692-3MGT-006? Or you worked out a way of stuffing a 15mm belt into a 6mm opening?
Hey Mike, The Belt is actually 6mm wide, you are correct about the part number. The photo is mine, the "-006" designation is likely not shown as the belts would be slit from a wider stock material. Cheers Anthony
I see. You are a wonder with the hands, Anthony One thing I noticed when researching GT3 belts is that the EU/Asia/Aus/NZ gets a much better selection than the US, where Gates is HQd. Strange...
Our range isn't that great either, that or I was calling the wrong suppliers. The belt I got came from Europe, think they were UK made. It took 6 months between ordering and delivery for me to get them in my hands. In fact I'd almost given up hope of ever getting them.
Really? The brochure I got on the GT2/3s came from the Australian distributor. It's called "PowerGrip GT3 Brochure AUS & NZ November 2010" Looks like CBC are the best bet in Melbourne - they are down as synchronous belt suppliers for Vic.
Yep - they even have the GT3 specifically listed: http://www.conbear.com/files/content.php?sec=products&sec2=power-transmission&sec3=gates&lang=en PowerGrip® GT3 - 2MGT, 3MGT, 5MGT, 8MGT and 14MGT If these prove to be problematic at long runs, there's always the carbon belts Gotta buy 50 feet, but.
No worries. I've about done finding all my hardware - found the low-profile hex bolts in China - nice man took my spreadsheet and told me what he could get me and what he couldn't - top bloke. Some real savings over Openbuilds prices - especially on things like the right-angle cast brackets, 30c vs $1.50, 50 stainless screws for 10c ea instead of 20c ea, steel L-brackets for 50c, not alloy ones for $1.25 and some nice, big right-angle brackets for 2060 series extrusions I will use to ensure my corners are square - 38c ea. Should be able to put my order in today - although I see they aren't fulfilling till the 31st.
I think you are quite right to say gt2 belts are substandard for use on 1500mm axis, my x belt didn't last one job before stretching. And constantly slipping,, tightening belt clamps to the point the screws go through the belt. Still haven't finished that job lol I've put gt3 belts on now tho I haven't tried them out they seem 100% stronger and they are tight under clamps so less tightening required so less chance of any damage being caused to the belt. If these stretch anytime soon I won't be repairing. Had I not got the gt3 for free I would have upgraded to rack and pinion and probably still will for x axis.
The only issue I have with the GT3 belts is being 6mm wide they are a fairly snug fit in the v-slot extrusion, not sure how long they'll last before they start fraying..time will tell I guess. I'm not far away from firing up my machine now, I'll provide feedback on how they hold up. I'd be interested in hearing about your rack and pinion setup if you go down that path. Cheers Anthony
Yes I see what you mean, let's hope not a. Rack and pinion - very simple, 2 extra v wheels underneath pinion to support the rack and pull up into pinion so they mesh and 1500mm rack spanning the length of the axis and secured at either end on a bracket so the rack is floating. Found a company that do both a 6.3 and 8mm bore anti backlash pinion with 2.5mm pitch so it seems the parts are readily available. Looking at around £200 per set. So not cheap but a good investment I feel
I looked at so many rack and pinion machines - but getting the hardware has proven very difficult (at my price point). Compared to rack, belt is just so much easier, and at the kinds of speeds and with the kind of gantry weight we are talking about, I just can't see it being an affordable or viable option, for me. Gates has a carbon version of the GT3 that apparently has less stretch than chain, so if I find myself screwing up too many cuts, I think I will head down that path before I go R&P. For someone in an industrialised country, it's probably an easy choice to make, but out here in the wilds of Borneo - the cost of shipping in 8x4s worth of rack is about US$500 - and that's from Misumi in Malaysia... Good luck- I would love to see the finished article.
Yep. You have no idea of the cost of parts and shipping. When I lived in the UK I complained about both - I would love to have UK prices (and selection!). I recently looked at an extrusion-based CNC kit from a US company - the parts were about $1500, the shipping nearly $3000. As it is, the shipping from OpenBuilds is costing me $235 for the wheels, v-slot and eccentrics - which I consider pretty good. The plates and the rest of the hardware adds another couple of hundred in shipping and with the spindle, electronics and steppers, my shipping bill alone is close to US$900
>>For someone in an industrialised country, it's probably an easy choice to make, but out here in the wilds of Borneo - the cost of shipping in 8x4s worth of rack is about US$500 - and that's from Misumi in Malaysia... I ship quite a bit overseas, mostly using USPS. While I'm limited on length (42" or about 1000mm), about 6 pieces of 20DP-20PA rack runs about $140 in shipping to Borneo. Still expensive but not $500.
And the cost of the rack? Sorry if you think I was lying because I didn't get an option to buy from some previously unknown vendor... but $500 was my quote - and the reason I haven't built a machine so far. Thanks for your contribution.
The 6' racks are $40.34/each. And wow, no, I did not think you were lying. I thought that Misumi was marking up shipping...a LOT!
They charge like wounded bulls for everything. A piece of 2020 aluminium I can get air freighted from China in a couple of days for less than just the unit cost of the same thing from Misumi. No doubt the quality of their part is good - better than the Chinese part, but when all I am doing is making a frame, I don't need a $60 piece of alloy - $12 is good enough. My apologies for the undeserved slight - I just got a shipping quote for 285 Pounds Sterling for 2 pieces of 8020... but the same piece to Australia - further from the UK than me by quite a few thousands of miles - is 96 pounds. We get the shaft on shipping here.
Hi Diane. Did I read that right? 6 Foot racks for around $40 dollars each? Where are you based, and can you put up some pictures and details for them? Gray
Going back to Gt 3 belts, no sign of fraying or catching due to width, but still same issue of belts slipping under tee nut. Colin robocutters actually supplied me with some new clamps that are almost like buckles, but unfortunately gt3 is too big to bend through the buckle slots. So I think the solution is to use 3 tee nuts at each end. Which means taking the corner brackets off and splitting frame to get them in on mine as corner bracket covers slot opening. But one tee nut just isn't up to the job. So note if you use gt3 use 3 tee nuts at each end! But well worth the upgrade from gt2. No stretching as yet anyway.
Good news about the belt, not so much about the slipping. Thanks for tip regarding use of extra T nuts.
worked out a way of using colins bolt clamps with gt3 belt put them on top.. and no need top dismantle frame seem to work very well.. think with gt2 you can put them into the slot like a tee nut but wont fit with gt3 unfortunately. and here:s the x - the way my gantries are made i had to cut the buckle down to two slots
That's a neat solution, I will definitely do this. There are two versions of the clip on the Robocutters site. Is there a difference? Which ones are you using Jonny?
Beg your pardon I'm using v1, think they are both pretty much the same, v2 slightly stronger if your going to bend. Here's the link https://www.robocutters.co.uk/proddetail.asp?prod=BeltAnchor&cat=47
Here's another issue I have found and thought I would share my solution to, is the pinion grub screw slipping and rounding out. I hope it's not just me that find the original grub screws round out with any descent Torq on them... In my opinion they are far too small for the Job. Another design fault that I have had to address. Here's my solution: Tap a much larger grub screw in there. I also filed a flat spot on motor spindle. Is solid now and can tighten and loosen without being in fear if rounding it off Can't really understand why they were so small in the first place???
