REV V-groove Ball Bearing Weight

Technical Kit & Additional Hardware
1

We are waiting for the REV Parts to come back in stock from AndyMark, but have a question while we are waiting.

http://www.andymark.com/product-p/am-2914.htm

The weight listed on AndyMark is .86 lbs, this seems extremely heavy to me. Other similar bearings list their weights as 1.4 ounces, which is much closer to .086 lbs. I am hoping this is a typo on the AndyMark site, but I wanted some one to confirm.

We are going to use 24 of these on our bot, and 20.64 lbs seems crazy, I am hoping it is closer to 2 lbs than 20.

2

Another website lists RM2ZZ bearings as 40 grams which is .088 lbs

3

Since these are currently out of stock, is there any reason to use RM2ZZ bearings instead of RM2-2RS bearings?

4

I don’t see any difference in dimensions, but I am not an expert on bearings.

5

I also looked it up from various sources and I believe it is missing a zero (.084 instead of .84)

Looking at http://www.revrobotics.com/product/rev-29-1014/ it is a RM2ZZ size. As others have said the RM2ZZ is around .084 pounds.

6

That does seem to be excessive. I think we have some of these in our build site; I’ll check this afternoon, and update with weight.

7

I can confirm, the weight is .084, it is just a typo.

Also they will be back in stock at AndyMark in the next couple days. RM2ZZ is a common bearing that you can get anywhere if you need it right away (but we are the lowest cost source that I could find anywhere online if you can afford to wait.

8

What about the bushings?

9

I spoke with both Greg and the people at AndyMark, bushings should be in today, and continue to trickle in over the next few days.

That being said AndyMark now lists them as back in stock on Saturday.

10

Yes the bushings should be received this week, but the qty is very limited. If you are looking for another solution and have a lathe, making them is not hard our drawing is on the web. http://www.revrobotics.com/wp-content/uploads/2014/12/REV-21-1029-DR-00.pdf Just start with a piece of 1/2 hex. To make the eccentric hole take it to a drill press or mill.

Another option for construction is drilling out 3/8 bolts. The amount of center offset is not that critical as long as you have enough flexibility that it can engage. For the concentric side, just use a 3/8 bolt and drill out the mounting plate.

Lastly another option is to buy the ones from Bishop-Wisecarver. They are more expensive, but available right now if you need them. The REV v-groove bearing system is compatible with their “Size 2” system. You might need to add a washer or spacer to get the alignment correct, but they will work.

Eccentric bushing - BWC Part number - BX2SS Price - 8.54

Concentric Bushing - BWC part number - B2SS Price - 4.18

I am sorry specifically about these bushings, 100% of them arrived to me out of spec from our mfg(so the bearings wouldn’t fit), they are replacing them with new bushings but in the meanwhile we are re-working them (I am literally standing a lathe working on every single one).

Greg

11

The 1" REV rails and Vee bearings show an expected date on 1/26. Since I can’t back-order from AndyMark, I am hesitant to order the bushings and plates on Friday 1/16, then wait 10 more days in hopes of getting the rail.

Greg - can you give us an idea of what quantities are heading to from the manufacturer to AndyMark and when? The new REV extrusion system looks awesome, but if I can’t get it earlier it will have to wait for the offseason to test. Good luck with your lathe work (I have a very deep personal dislike for poor manufacturing QA/QC for tight tolerance machined parts).

-matto-

12

Thanks for the part print! I hadn’t seen that on your website yet. Tonight I had a student download the assembly that was posted, open the .step file in solidworks, use the feature recognition tools, and then make a 2-D part print out of it for our Precision Machining class because they are going to help us out in making these. Now I have my answer key!!! :slight_smile:

Good luck with the lathe work and thanks for being sooo dedicated! My local salesman for 80/20 was in today and he loves your stuff! He may be getting in contact with you…