White or Gray seat rollers & bearing size

[Carl Watts]

Just trying to work out if the White rollers were used on the Model D and what the bearing size is for them. From the pictures on the net I have seen both used. Which is the "Newer" roller ?

The Grey rollers are on my Model C and used a R6Z bearing. I want to know what bearing fits the White rollers. It is not the same size bearing.

It would appear to have an OD of 57/64" but was it still 3/8" ID ? can someone supply the bearing number please.

[c2jonw]

Carl,

White and grey rollers have both been used on the D, with the white ones being used for at least the last 4 years. The grey is a molydisulfide filled cast nylon while the white is Delrin. The Model C had both the grey material and an oil filled cast nylon that was green. All three of these materials work very well though the delrin is a little less expensive and it seems to run cleaner on the stainless rail.
We've used R6 double shielded bearings for both the top and bottom seat rollers in the C,D and E machines. Not sure where you're getting the 57/64' OD from- that's 1/64" or .016" greater than the 7/8" OD of an R6- maybe a measuring error?
C2JonW

[Step234]

Jon
What is the composition of the "whte" B's?

[Carl Watts]

Yes a definate problem with the bearings required for a number of Delrin White rollers I have as well. Definatley 57/64" the 7/8" R6 bearing just flops arround. Must have been a bad batch that was made at some point in the distant past. No big deal I'm going to make up some race rollers by opening up the holes a little more and sleeving them all the way out with alloy tube machined to suit the R6 bearings to produce a superiour seat roller. Also holding the rollers with 3/8"x 4' shoulder bolts & some custom washers to get a better fit on the bearing ID as well. Don't worry it's just me (and a guy called Tim) I modify everything, even the lawnmower.

[c2jonw]

Carl, the white model B rollers are delrin. So, regarding the rollers you have in which the R6 bearing "just flops around"- are they old, used rollers? There is a tendency, over time, for plastic to deform under pressure, which in the case of the rollers can result in the hole that the bearing is pressed into to enlarge. Note the main problem you are likely to encounter with drilling out and sleeving the roller is the concentricity of the bore to the running surface of the roller. You may want to skim this od with the roller running on the bearings in the new sleeve. Of course this will reduce the OD of the seat roller, possibly necessitating a relocation of the bottom rollers to keep the seat snug on the rail- or some other solution? Some projects just never end.....C2Jon

[Carl Watts]

The rollers are brand new, I have a bag of them. Either they were machined wrong or someone here in NZ made a batch themselves on a CNC lathe, which I find unlikley but possible.

I have full access to a Lathe so the finished product will run dead true. Have had experience already with bearings running in a plastic housing, as you said the problem is they get loose over time, however with an alloy sleave that is a tight press fit and precision machined internal diameter that will not change to suit the bearing this will be less of a problem as the load will be spead across a greater area rather than just the width of the bearing itself.

I love projects

[c2jonw]

Curious, we never sell rollers without the bearings in them, in fact we purchase them from our vendor with the r6 bearing and spacer installed, so it seems very possible that these are not ours. I wonder if they were sized for a metric bearing with a 22 mm OD (which we've never used) Where did you get them from? PM me a photo if you get a chance. So with the origin of the parts in question the material that you're working with is an unknown. There are ways of determining a plastic type which you may be familiar with. C2JonW