Alternate parts

I am working on getting the mechanical stuff for the Darwin together. Unfortunately the McMaster bill was over $370 by itself. I don't have that kind of cash available after paying for my car and other bills.
Basically I'm trying to be cheap, if anyone else wants to follow my lead this is what I've done so far to drop the price:

Quote

1--M5 screws-buy 1(100) pack of 50mm. More than you need, cut them down with a dremell.
2--M3 screws-buy 1(25) pack of 50mm and 1(25) pack of 40mm. Same as above, cut down to size.

(this already saves you $60)
3--M8 threaded rod buy from amazon (save another $60)
4--8mm smooth rod from [www.smallparts.com] at $2.8/yard (save another $15)

That's already $135 saved.

My main concern though is the MXL belt. They also have the .080 pitch 1/4" but I can't understand the pricing table, any ideas? [www.smallparts.com]
Also, couldn't I just mold the other 3 of the Z pulleys? I saw something about molding them on the wiki.
Let me know what you guys think or if you have any other suggestions.
thanks
Dylan

You can mould the pulley and you only need 1 pulley to mould all the others from the Z pulley will work fine with 20 tooth as well, the difficulty is keeping the run-out acceptable, we supply moulded pulleys but have had a lot of trouble with run-out so now I turn the bore on a lathe and as such keep the run-out acceptable, also moulding for a few off is expensive as the silicone is not so cheap, by all means give it a go but i would only suggest this if you want to learn a new skill, as with all things the learning curve is always a different shape to what you hope for

I intend to try cable with multiple wraps on a drum this would be very much cheaper and might be worth considering as it also save the belt cost.

---

Ian
[www.bitsfrombytes.com]

Dylan,
You could also look into [www1.mscdirect.com]
that was where I bought most of my parts well there and Home Depot.
I did buy my belt from Mcmaster carr but everything else from MSC including my pullies which were made from plastic..

Bruce W.

Dylan:
>My main concern though is the MXL belt. They also have the .080 pitch 1/4" but I >can't understand the pricing table, any ideas?

These are closed loops of belt, aka "endless loop belt".
The first entry, TB4-036MXL, has 36 teeth, and is 2.88 inch in perimeter.
The last entry is only 18.00 inch in perimeter. This is no good.

I think you need ~16 feet of belt, so you'll have to go with mcmaster.com or sdp-si.com . They'll cut you some from a reel.

Bruce W.:
>I did buy my belt from Mcmaster carr but everything else from MSC including my >pullies which were made from plastic.

MSC is cheaper, right? We should get their data into [parts.reprap.org]
Would you be interested in entering the part numbers into our spreadsheet?

Hmm... It said something about date, that's what was confusing me.
My local Home depot had 5/16 steel rods, but they were 3.80 compared to the 2.80 on the site I mentioned above. Last time I looked though, they only had 1 left.
The rrrf store might be able to get some of that stuff too by buying in bulk from the manufacturer. (just a suggestion, I'm sure the motors will be a good indicator if that premise will work.)

I got my MDF today, my local ACE didn't have it and I had to get 2'x4' at home depot for about $7 something. I might use the rest to mount the boards and power supply to.
I might be cheap, but I don't make a lot and am being "frugal".
The BOM might be nicer if it had a price listing for the part from each place. At least under the product details page. I was going to get everything from the same place, but I think I mentioned before about Amazon having some stuff way cheaper than mcmaster. I'm not sure how easy that would be.


Thanks for the suggestions, I probably won't be too into this until I put aside the cash for the parts.
Dylan

mcmaster is known for being expensive. They have everything, though, and ship

For threaded rod and smooth rod, try your local steel supplier in the yellow pages. It should be cheaper than best buy. (They stock the stuff in big lengths, I ended up getting my rod cut down to 10 foot sections, and then I cut the smaller lengths at home.)

You are right I believe it is 16 ft. that you need I will pull out my invoice today and get you some part numbers to compare...

Bruce

here is what I got from both MSC and Mc Master Carr

MSC
the pullies
04895132 .08P 20 GR DBLFLG MH MXL PULLEY W/ALUM HUB 6 ea 2.0500 $2.05
05399704 .08P 62 GR DBLFLG MH MXL PULLEY W/ALUM HUB 4 ea 2.3000 $6.90
I had to drill out the holes to a larger size but they did not cost a lot.
also they had very good prices on screws look at the import line..

Mc Master Carr

1 7959K21 TRAPEZOIDAL TOOTH NEOPRENE RUBBER BELTING, .080" PITCH, MXL TRADE SIZE, 1/4" WIDTH 16
FT 16 0 1.65
FT 26

I did order 16 ft of belt and it was just enough so measure twice cut once.. I have less then a ft. extra and I thought 16 ft was a lot at first but was wrong it wasnt.

As for steel rod and bar stock I used 5/16" from Home Depot and I also used inch screws but then again I had my parts from wood unlike the plastic molded parts which have nuts embedded and would require screws be metric you should be able to get away with 5/16 rod though..

Bruce Wattendorf