rudy - Posted - 02/09/2012:  05:39:42

My guide for cutting block rim segments to correct size is available at my website (HERE) as a free downloadable PDF that prints out full size segment patterns for 11" and 12" rims in either 5/8" or 3/4" wall thickness, and 8, 12, or 16 segments per layer.  The image shown here can be used to read the dimensions if you zoom in, but the printable PDF is MUCH easier to use!

Edited by - rudy on 02/09/2012 05:40:33

Iderhobanjer23 - Posted - 02/09/2012:  06:00:52

Rudy,
Thanks for all the info you share. I'm a big proponent of free-flow of information on the internet. It only helps us all. You could charge for these things, but things like money seem small when compared to continuing such a long and beautiful tradition that needs help. Thanks.

dickinnorwich - Posted - 02/09/2012:  06:35:03

Randy:

Funny story:

A few years ago, a local fellow came to the house seeking my help on how to break into the banjo rim-making business. He was out of work and I felt badly for him. I spent about 3-4 hours with him and taught him everything he would need to know to get started. I even did a search for him and located a low cost lathe. Before he left, I gave him a basic block, just like you have shown in the illustration above, that he could use as pattern for building block rims. Like you, I felt good about sharing. But as I have learned, no good deed goes unpunished.

A week or so later, an add appeared on EBay. The guy was trying to sell the block I had given him for $19.95!!

This is the same guy who, a short time later, wasn't wearing a mask and had a block explode in his face. He published a picture of his bloody face on EBay (why, i don't know). As far as I know, that was the end of his rim-making adventures. 

mbanza - Posted - 02/09/2012:  06:59:30

I've begun using a scarf jointed block layup for rim construction.  Not much different from the Helix layup except it's three layers without the inner pieces.  Joints are very strong.

Off axis joinery

Stivini61 - Posted - 02/09/2012:  07:28:05

Has anyone compared the prevalence of tearout at the glue joint (or elsewhere on the billets?) for traditional butt joined vs. scarf joined block rims?  I know Randy uses a bandsaw to get close, then sands his blanks to final size and surface, but many of us spin rim blanks then stick sharp pieces of metal into them.  One of the eternal pains in my neck are the very small chips that come off the area adjacent to the joints on my butt joined rims.  A quick look at the scarf joined diagram indicates that the orientation of wood strands in that joint would favor less tearout.  I'm assuming that Verne cuts his billets with the grain running parallel to the long orientation.  Is there a consensus on which joint yields the best result OR on how to turn a butt joined rim blank with minimal tearout? 

Moving sharply from higher quality/ability toward lower quality/ability the production chain in my shop goes this way:

Lathe - Tools - Wood -------------- Tool Sharpness -------------------------------------------------------My Ability

The above diagram might explain everything, but thanks much anyway for your ideas regarding these question. 

mbanza - Posted - 02/09/2012:  07:54:15

Stephen, yes grain is generally oriented parallel the long axis of each block.  I've used butt joints too.  My experience is that the tear out with 45 degree scarf joints is minimized on one side and similar on the other to block construction;  you can choose which by how you orient the layers.  I prefer to orient to minimize tear out on the outside of the rim then use a scraper on the inside to smooth it.  I have yet to try this with other than eight blocks.

rudy - Posted - 02/09/2012:  08:11:43

Steve thusforth has quoted:

"I know Randy uses a bandsaw to get close, then sands his blanks to final size and surface, but many of us spin rim blanks then stick sharp pieces of metal into them."." 

Hi Steve,  The vast majority of my rims are made up by sticking sharp pieces of metal into them, too.  The difference is that most of my rims are pattern routed using a top bearing equipped carbide pattern following router bit instead of a lathe.  I do hog off the excess material with the band saw, though. 

I recommend the sanding methodology for neophyte rim makers who want to avoid the tear-out issues that you are referring to.  Any rim that uses block construction will be more prone to more tear-out than laminated rims, but that comes with the territory.  What you have to look at is exactly what your cutter is doing, be it lathe, router, or whatever.  If you think about how the mechanics of all this works you'll realize that the fewer number of segments you have the greater chance for tear out along the join.  It basically boils down to the grain angle where it intercepts the cutter.

For me, Verne's scarf or my equal angles have much the same issues, and I place little emphasis on joint strength, as it only really has to hold long enough for machining until the next overlapping layer is added.

You have to consider the rim as an integrated assembly, and often I'm making rims where the block construction is only a 3/8" wall, additional overlays of more highly figured 1/16" veneers clad to the inner and outer walls of the rim, then both exposed ends capped with integrated tone ring and rear rim cap.  I could drive a large truck over them with little damage incurred.

mbanza - Posted - 02/09/2012:  08:49:14

Please post the pictures of the large truck test.

rudy - Posted - 02/10/2012:  04:55:40

quote:

---

Originally posted by mbanza



Please post the pictures of the large truck test.

---

 Verne, I've got a shot of a mid-size truck on my rim somewhere if that's OK, but I'll have to find it on my hard drive.

mbanza - Posted - 02/10/2012:  08:19:33

Cool, I hope you find it, and by the way, kudos for making so much much of your knowledge freely available.

Dexter - Posted - 02/10/2012:  11:34:43

Thank you Rudy...I just printed it. The information on your website is outstanding.....Rick

rudy - Posted - 02/11/2012:  11:31:17

You're entirely welcome, I only aim to please!

slou92 - Posted - 02/11/2012:  13:25:47

One block for 19.95?  Wow, I have a gold mine in my shed.....

That's pretty funny, thanks for sharing that.

Waltj - Posted - 02/12/2012:  09:32:08

Thank you Sir

Walt