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Bill40718 07-10-2017 11:21 AM

Tuning up a Rock BR - Updated
4 Attachment(s)
DISCLAIMER: This worked for me, YMMV!!

My Rock BR was clunky, jerky and anything but smooth in operation as I got it.
As I could not afford a higher quality rest, at this time anyway, I thought I’d see what could be done with the rest I have.

On my first attempt I tore the rest completely apart and did some polishing on a couple moving parts, the bearing face of the height adjustment wheel and the gib surfaces of the cross slide. I also tried to find a way to polish the screw threads on the height adjustment screw and the leg leveler screws. With no machines available there wasn't much I could do. I reassembled the rest and found nothing much improved. Maybe the cross slide moved a bit easier and had less backlash, I’m not sure.

For those folks interested in performing these upgrades, here is a link to the McMaster-Carr site where you can find the correct delrin parts and bearings.



Later on I was emailing with Leo Bourne, the guy I bought my CVBR stock from, and mentioned the Rock BR project. After some discussion we started collaborating on what to do to improve the rest.

Here is what we came up with.

1. Disassemble your rest. Remember how it comes apart or take photos!

Attachment 90729

2. Using 400 and up wet/dry paper on a flat surface, polish parts 1, 2, 3, and gently polish the angled gib surfaces on part 1. Maintain the original the angle on these gib parts. Polish to whatever luster you feel like working to.

Attachment 90737

3. If you are up for additional work, sand and polish parts 4 and 5 in above photo. Leo did, I didn’t.

Modify the tip of the mariners wheel lock screw, photo below, to look like the lower lock screw. Basically remove the threads for ” or so so the tip will fit into the way in the main height adjustment screw. This will allow us to throw away that black part in the photo below and lets the rest lower much more smoothly.

Attachment 90745

I switched the 2 lock screws. As the gross adjustment is used much less often, I put the modified lock screw there. And used the factory screw to lock the mariners wheel.

I also noticed that the way, look at the photo in the next post, looked as if it were machined with a hammer drill. A bit of filing and sanding smoothed it out considerably. Works smooth now.

4. We will discard the parts in the photo below.

Attachment 90753

Bill40718 07-10-2017 11:21 AM

Tuning up a Rock BR - Updated
4 Attachment(s)
5. Now make or buy 2 Delrin(UHMW) washers with the appropriate diameters. These washers will replace the bearing discarded in step 4. See photo below.

Attachment 90761

6. Lightly lube the main adjustment screw and reassemble the upper cross slide assembly. Now is the time to position the thrust bearing if you have decided to use them.

As you assemble the cross slide be sure to adjust the backlash.
You adjust the backlash by how tight you set the nut holding the whole assembly together. Trial and error with this adjustment. Look under the mariners wheel at the end of that funky arrow in the photo below.

Attachment 90769

7. Assemble the upper assembly to the base assembly using the Delrin washers as shown. The smaller washer goes on the main adjustment screw. The larger washer goes on top of the gross adjustment post. An appropriate sized thrust bearing could replace either of the Delrin washers.

Smaller washer on the shaft.
Attachment 90777

Larger washer on the gross adjustment post.
Attachment 90785

Throw away that black part that locks the height adjustment. Its inside the main casting, behind the mariner wheel lock screw, and presses against the adjustment shaft. That is the thing that causes the rest to not lower smoothly when you turn the mariner wheel.

Thats about it for the adjustment mechanism.

Bill40718 07-10-2017 11:22 AM

Tuning up a Rock BR - Updated
2 Attachment(s)
Now to make the rear leg leveler screw work much better, buy or make a decent foot. That point on the adjustment screw just doesn't let it rotate easily or smoothly.

Below is a photo of Leos solution.

Attachment 90801

And below is a photo of my rest and 2 different style feet. I bought a couple O.D. bearings (with a single lip) and mounted them as shown. I like Leos version and my Delrin version, but all the parts are at Ace to modify Dr. Heckel's version. I built it with washers, 1 rubber washer and 2 fender washers, a stop collar with I.D. and a OD bearing.

Note: The Delrin "bag" and "ears" did not work well in the initial configuration, as shown, and were abandoned.

Attachment 90793

Leo is no longer supplying tune up kits. The McMaster Carr site, linked to in the first post, has all that you will need.

Im pretty happy with my rest. The time, money and effort expended was minimal and the results are, in my opinion, are worth it.

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