Beware of Pololu.com

Pololu.com is a bad apple!

UPDATE BELOW

Pololu.com will not issue me a full refund for the order I cancelled before it shipped. I got a call back from them this morning to confirm the cancellation of the order I placed after their normal business hours yesterday, but they then informed me they could not refund 3.5% of the order, the cost of credit card fees.

I was the Manager of Information Systems (and webmaster) at a busy online retailer for a number of years. We did millions of dollars a year in online sales. We never charged any such fee. I was surprised to hear about this fee on the phone, and angry, so it wasn't until after I'd argued with the manager at Pololu.com for a while and hung up that I realized what the problem was. They process the credit card transaction immediately when you place your order.

We never did that where I worked. We only processed the payment when the order was shipped. There are two parts to any credit card transaction. First the transaction is "authorized" at which point the card vendor says you have sufficient credit to fulfill your end of the bargain and the merchant is guaranteed by the credit card vendor that they'll get their money, and that amount is set aside. Then, later, the transaction is "processed" at which time the funds are actually transferred to the merchant's account.

While apparently it's not illegal to process payment before the order is shipped or service is rendered, it is against the terms of service agreements for Visa and MasterCard. I used a Visa. I have no reason to believe this vendor has any explicit exception to the Visa and MasterCard terms of service agreements, so I believe they are in violation. The TOS on the pololu.com web site (and agreement to it incorporated in placing an order) does not obviate their obligation to honor Visa's TOS.

I can appreciate that their ecommerce software, if it's cheap, might make that distinction difficult, or perhaps they simply don't know how to configure it properly, but that's not my problem. They need to change their system, their business practice, and their TOS. Until they do, I do not recommend anyone buy anything from them.

I will be happy to update this post when or if they change their policy and issue me a full refund. I'll also be happy to update this post if they can give me a true and satisfactory explanation for how they can process a payment before shipping and not violate the VISA terms of service.

UPDATE (5-5-2011): Lienna of Pololu.com responded to my follow-up email with this:

Thank you for the additional information. We were not aware of a requirement to delay the charge for an order until the shipping date but are investigating now. In the meantime, we have refunded the remaining $5.44 from your original payment. You may also still use the coupon on your next order. Please contact us again if you have any questions, remaining concerns, or new information for us. Thank you!

So that's responsive at least. I revise my opinion from "find someone else," to, "use them if you can find a part, but keep an eye out and complain to the credit card company if they don't give you a full refund." Hopefully they'll revise their return policy and I can give a more enthusiastic endorsement.

Rotten apple photo courtesy of cooljinny.

Important Lesson About Stepper Motors

Torque! Specifically, holding torque.

Before you order your 5 stepper motors for the RepRap Prusa Mendel, you should read the RepRap wiki about stepper motors.

Here's what tripped me up: I'm using the Wade's Extruder design, which recommends a motor with a holding torque of 5 kg*cm. If you read the above article about stepper motors, you'll know what that means. So, when you go shopping for your Nema 17 stepper motors, you need to make sure they are 24 x 24 mm in size, with a 21 mm shaft length, and a 5 kg-cm holding torque. My mistake was to believe the parts list that came with the printed plastic parts, which was WRONG and recommended a Pololu stepper motor of the wrong size and power. Instead the RIGHT stepper motor is something like the Kysan 1124030 Nema 17 Stepper Motor offered by UltiMachine.  A helpful tool while shopping is the torque conversion tool online.

I believe the seller of the parts was trying to be helpful, but just googled for Nema 17 stepper motor and picked one without realizing the significance.

Project Update: Today I just went nuts online and started ordering everything left to order. I even bought a 5 lb spool of the plastic filament to print with. Obviously, I'm in an optimistic mood. All that's left to buy, then, is the electronics. UltiMachine is currently out of stock on the RAMPS complete pre-assembled kit. I'm going to be doing good just to get the mechanics together, and I don't even want to try the soldering. Total for the day $555.09!

Getting Help Building a RepRap Machine

There is a lot of help available for people building a RepRap machine. First thing I did to find help was to use Google and put together "reprap" and "kalamazoo" as search terms, since I live in Kalamazoo. I didin't find a lot with those terms, but if you were to do that now, the BuggerIT blog is first, second and third in the results. Hopefully this blog will be a resource to anyone in Kalamazoo, Michigan looking to build a machine, and of course anyone local who reaches out to me will get a response. I'm excited to help spread the word here in town.

You can also try to locate a local hackerspace. Members of any such club will almost certainly have heard of the RepRap project, and may even have a working one for you to see in action. In Kalamazoo there is a group that might roughly be called a hackerspace, but I couldn't find any evidence of RepRap or desktop/home CNC in anything they had online. Also, it just didn't seem like a place I'd like to go, so I guess I'll have to start my own hackerspace in Kalamazoo that's more my style!

If you expand your search to the state or provincial level, you will find some level of support there. In my case there is a Google Group called RepRap Michigan which is somewhat active. I have posted there and gotten responses. I think I found the group through the RepRap forums or the RepRap Map.

Expand your search from there and you can go straight to the global community. The first stop, of course, is the reprap.org web site itself. The videos available with the build instructions for the Prusa Mendel at least are very instructive. The best place to look for help of all though, is the RepRap IRC channel. On the IRC channel you will find all the people who are actively involved in the RepRap scene, and because it's promoted heavily as a source for help, also by beginners like you and me. I just spotted prusajr himself.

Other recommendations:

• RepRap IRC  (because it's worth mentioning twice)
• RepRap Blog
• RepRap Wiki
• RepRap on Twitter
• RepRap Log Phase (blog)

Project Update:

The video above is a test of what the video quality should be when I get started with project documentation. I'll have a second camera over my shoulder looking down on the table for a detail shot. My plan is to video everything and go step by step through the process in excruciating detail. The videos on the assembly page by RepRap Log Phase are great and all, but I think they move too quickly and use terms an absolute beginner might find intimidating and unapproachable.

Hunting Hardware for the Prusa Mendel

Like with the printed plastic parts my original intent was to try as best I could to acquire the materials locally instead of relying on the Internet to deliver the pieces to my house. As with the printed parts, initial efforts proved frustrating and in the interest of getting on with it, I wound up on the Internet anyway.

My parts list, as shown in the parts document that accompanied the assembly instructions and printed parts.

It wasn't a complete failure. First I started at what is the closest thing we have to a mom-and-pop hardware store of ye olde days, True Value Hardware. There I got zip ties, 5/16" nuts and washers, plus a handful of #8-32 nuts and washers, and one M8 x 50 Hex Hobbed Bolt and nut. I'd asked her for two nuts but didn't realize she'd given me just one, so I'll have to go back. I could have gotten the 5/16" threaded rod there, but they wanted something like $21 for one, 6' rod. Umm, no thank you. McMasters had them listed for less than $5 ea.

Total spent at True Value: $17.50

What it would have cost online: $23.75 before shipping

Lowe's was my next stop, and there I got threaded rod, and the fender washers.

Total spent at Lowe's: $19.16

What it would have cost online: $31.91

So far, so good. But those were the easy parts. Nobody up to that point knew what drill rod was, and nobody had any. The guy at Lowe's did give me two important tips, though. He was concerned that I wouldn't be able to thread a nut on to the 6' length of 5/16" threaded rod I had him cut in half, because, he said, the cut messes up the threading where it's cut. To avoid that problem he suggested threading nuts on the rod on either side of the cut and then wind them off to smooth out the thread. Fantastic idea. Second, he told me there was a fastener store in town called Fastenal, and they might have the other parts I was looking for.

Fastenal had some of the parts, and ordered some more which should arrive Friday, but some parts are still missing. From Fastenal I finally got the drill rod (well, 2 of the 3 pieces I need), M4x10mm bolts, #4-40 x 1” cap bolt, #4-40 washer, and #4-40 hex nut.

Total spent at Fastenal: $50.77

What it would have cost online: $21.84

Ouch. So, the score for this round is: $87.43 for the home team, $77.50 for the away team.

Online is probably only beating local by the amount of shipping, or less, but as I get to some of the parts they had to order special for me, the price differential increases. For the metric bits listed under the Wade's Extruder section of the build materials, I will definitely have to go to McMasters if I want to keep the cost down. The brass bushings were the hardest to locate nearby. I got a couple leads from Fastenal, but it'll just be easier to get them with the other screws and nuts I need for the extruder.

Mendel Printed Parts Arrived

The printed parts for the Prusa Mendel arrived today, and as you can see, I'm very happy about it. It was very quick in arriving, and they came packed in a ziplock, surrounded by the air-bag wrap you get from Amazon, and everything seemed to be in ship shape. I'd received the parts list and assembly instructions specific to this printing of the parts via email from the eBay seller. This is important because the project is constantly changing and you need the instructions that go with the parts being sold. I was sure to check the parts I received against the parts listed in the assembly instructions to ensure I had everything.

Overall the quality of the parts were satisfactory. Some were better than others, and all had a glossy, corrugated surface on one side, probably from the heated bed on the manufacturer's Thing-o-matic printer. 

The side opposite of the glossy finish was the expected pattern of extruded plastic, criss-crossing the surface. The burrs and flash that appears on the part was also expected and I'm sure will be easy to clean up when I get started.

This apparently is a tricky part for the Thing-o-matic. The glossy "bottom" of this part has some apparent defects and while this bothered my wife, who thinks this part wasn't very well made, I'm not so concerned. She's probably right that I wouldn't want to stress it very much for fear it will break, but that's likely true of most of the parts. I will want to print extra parts as soon as I get it running so that if something does go wrong I can repair it quickly without having to buy a part off someone online. Also, the large hole on this particular piece is especially messy. I'm not sure what the issue is there, but it's probably not a big deal. I might dab some glue in there to firm up the filaments and then ream the hole.

The gears are especially important, and I imagine somewhat difficult to get right. This one is really quite nicely done I think, but the smaller gears are a little less well defined in the teeth area, and vary from the diagram in the instructions in that the hole where the tension screw goes, so the gear can grip the motor shaft is not complete on the outside. The part of the hole on the inside edge of the slot for the nut that threads the screw is complete, so it should be fine, but perhaps I might try printing better small gears and replace them immediately when I get the chance.

Some pieces were printed very close together, and come stuck together. Again, not an issue, but the smallest part shown here might cause me a bit of trouble if I'm not very careful. They are quite firmly stuck together. 

I won't have time this weekend to get the hardware, but that's the next step and I'll hit Lowes on Monday.