Kurt Kemp - Posted - 07/12/2011:  09:19:46

I am going to build a ball bearing pot just for kicks. I bought a 1925 ball bearing / spring set and Dick Guggenheim (dickinnorwich) is going to build a maple/cherry rim for it. The question neither him nor I can answer is the measurements of such a rim. As in hole spacing, depth, diameter, etc. Does any one have these measurements or a blueprint to this type of rim?

Mumble Peg - Posted - 07/12/2011:  11:06:48

Tony Pass has experience building this type of rim.

tonypassbanjorims.com/

bnlholic - Posted - 07/12/2011:  13:30:56

Hi.

I've thought about doing the same thing for several years.  I'm curious how you're going to mfg the "shotgun" skirt that was on that model.  I'm in East Lyme, 15 or 20 miles from Dick Guggenheim.  He saw my ball bearing banjo years ago-installed a shim to lower the action for free.  Thanks Dick.  I have an extra 1925 ball bearing rim that I'm not using right now.  I'd be happy to let Dick examine it.  However, it doesn't have the correct coordinator rods.

Dan

dickinnorwich - Posted - 07/12/2011:  14:41:06

quote:

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Originally posted by bnlholic

Hi.

I've thought about doing the same thing for several years.  I'm curious how you're going to mfg the "shotgun" skirt that was on that model.  I'm in East Lyme, 15 or 20 miles from Dick Guggenheim.  He saw my ball bearing banjo years ago-installed a shim to lower the action for free.  Thanks Dick.  I have an extra 1925 ball bearing rim that I'm not using right now.  I'd be happy to let Dick examine it.  However, it doesn't have the correct coordinator rods.

Dan

 

 

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Wow, Thanks, Dan. That's great. We're having our regular Tuesday jam tonight at the house (7pm) if you're interested and available. Otherwise, I'll make arrangements to come down.

Fathand - Posted - 07/12/2011:  19:54:31

My 1925 Ball bearing has 3 different washers in each of the holes, 1 under the spring and 2 on top, the topmost washer has the largest chamfered hole in it facing up for the ball bearing to sit on.

Also there is a very thin square profiled ring about 3/32 square that is not very visible, maybe it is dirty or maybe it was finished the same dark colour of the banjo. This rides under the above mentioned shotgun skirt. In 1926 ther eliminated the holes in the shotgun skirt so I believe you could use either style.

Did you get the flange? My flange is in 2 semi circular pieces that go under the tube. Half of the holes are larger and these do not get washers under the hook nuts. this is so you can remove the flange by undoing about half of the hooks and not lose your head tension, if you want to play open back without a flange digging in your leg.

I would love to know which Guarantee label you have in the rim when you get it and what the serial number lot is. Mine is 8041 and has the early "This Gibson is Guaranteed" label.

I believe the rim dimensions are the same as tube and plate style rims.

Feel free to ask anything

dickinnorwich - Posted - 07/13/2011:  08:34:58

quote:

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Originally posted by Kurt Kemp

I am going to build a ball bearing pot just for kicks. I bought a 1925 ball bearing / spring set and Dick Guggenheim (dickinnorwich) is going to build a maple/cherry rim for it. The question neither him nor I can answer is the measurements of such a rim. As in hole spacing, depth, diameter, etc. Does any one have these measurements or a blueprint to this type of rim?

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Here is a photo of Kurt's BB parts. Can anyone help us identify them as to the year?

banjomartin88 - Posted - 07/13/2011:  08:54:44

1926

dickinnorwich - Posted - 07/13/2011:  09:05:54

quote:

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Originally posted by banjomartin88

1926

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Thanks, Dan.

I just heard from John Miller (NDJohn) and he said the same thing. 

Is there anything (really tricky) I should know about making the rim? I know there are 24 holes for the springs but I don't know about the spacing. Are they spaced evenly, every 15 degrees or are they spaced more like a notched tension hoop? 

banjomartin88 - Posted - 07/13/2011:  10:12:19

quote:

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Originally posted by dickinnorwich

quote:

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Originally posted by banjomartin88

1926

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Thanks, Dan.

I just heard from John Miller (NDJohn) and he said the same thing. 

Is there anything (really tricky) I should know about making the rim? I know there are 24 holes for the springs but I don't know about the spacing. Are they spaced evenly, every 15 degrees or are they spaced more like a notched tension hoop? 

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From what i remember when I took mine apart to take the conversion ring out and put it all back original, the holes were spaced evenly.  But I am not 100 percent sure.

Kurt Kemp - Posted - 07/13/2011:  13:27:46

Thanks for all the responses, both in the forum and offline. I think we have enough info to make a go of it!

Kurt Kemp - Posted - 07/13/2011:  14:57:49

Thanks to John Miller for the info below. I paste it here for everyone's benefit. Thanks Dick for scratching around to find it!

> I have 8482 apart and made the following measurements

> on the rim. The holes are 3/8" D. and approx.1.070"deep. The

> rim is .790" thick at the bottom. .625" at the top,and 2.220" tall.

> The OD is11" at the bottom and10 11/16" at the top. All of these

> dimensions vary by a few thou. or so. Hope this helps.

>

>

>  I measured 10 springs, they varied in length from

> .735 to .763.  The average of the 10 was .750.

> The top hole is 5/16" to the center of the hole.

> The lower one is 1 5/8"  to the center.

> A No.19 [.166] drill bit best fits the holes.

NDJohn - Posted - 07/13/2011:  19:25:52

Good luck with this project, Kurt and Dick. I should point out that these measurements were furnished to me by a fellow Hangout member when I also began such a project.

Finally, Dick, the holes are drilled to match the pattern of the tension hooks. I'll post a picture later this evening.

Best,

John

NDJohn - Posted - 07/13/2011:  19:40:23

As promised...

Ball Bearing Rim