crossrod size

[dgalloway]

What is the most common diameter for crossrods? I am thinking 5/16 square steel but wondering if it would be strong enough. The rods will be approx. 8 1/4 in. long and rounded to 1/4 in. going into Oilite bushings. Thanks for your input as always.

[ljs]

My early built GFI had 5/16" aluminum cross-shafts and they were strong enough. It was built in 1994 or 1995. It was a S-10. I think there would be no problem at all with 5/16" steel. I believe the newer GFIs have gone to steel cross-shafts, but I could be wrong on that. I owned a S12 briefly that I think had steel shafts. Maybe a S10 with it's narrower body would be different than a SD10 or a D10 though.
LaVern

[richard37066]

My GFI D10 had steel cross shafts.

[Storm Rosson]

My Fessy has 5/16" steel square shafts.

[Bent]

5/16 steel is ok but overkill IMHO. Too heavy for one thing. I use 3/8" aluminum which I find to be adequate. I do use support posts in the middle so they don't flex when activated.

[ljs]

5/16 steel is ok but overkill IMHO. Too heavy for one thing. I use 3/8" aluminum which I find to be adequate. I do use support posts in the middle so they don't flex when activated.

Bent, I have to agree with you on that. I wonder if the main reason the manufacturers go with steel is that they think cutting down on the manufacturing price is more important than cutting down on the weight. I also know when I had my GFI S10 and added some levers and pedals I had a hard time finding 5/16" square aluminum and ended up getting 3/8" square and milled it to 5/16". I haven't looked lately but a year or so back I still hadn't been able to locate a source for 5/16" square aluminum. The reason I went with the 5/16 is that is what my GFI had and I wanted it to be the same size throughout.

LaVern

[Bent]

LaVern, Wow GFI used 5/16" aluminum? That should be good enough proof that alu is strong enough. Do they also have a post in the middle of a long cross shaft?(or a rail maybe) This is important since there is a wee bit of flexing when activating a knee lever. I feel a marked difference in the KL with and without the post. Alu is surprisingly strong and tough. I remember when testing my latest bell cranks. The arm on these measure 1/8" by 3/8" and look rather weak, especially since it has has 10 holes for the pull rod. I remember testing by putting a bell crank in the vise and hooking my digital scales to the outermost hole. I pulled it to 90 lbs with no sign of breaking or bending. The highest stress on a bell crank in the guitar is around 30 lbs

[dgalloway]

Thanks for the posts! I think 5/16" steel in my case might be the right choice based on your comments. Looks like 5/16" steel or 3/8" alum. both are used by builders and both work, so no right or wrong. What Bent and LaVern have said about weight makes sense, the aluminum will definitely factor in, only thing I don't know is if you have to use high strength aluminum or can use 6061. If you use 6061 then the cost vs. steel is about the same from McMaster-Carr. The weight of the guitar for me is not of great concern because I do not plan on carrying it around, more concerned about how it plays and the tone, which brings up a question. Does the weight of the guitar have any effect on the tone or possibly the sustain?

Thanks

Dave G.

[ljs]

LaVern, Wow GFI used 5/16" aluminum? That should be good enough proof that alu is strong enough. Do they also have a post in the middle of a long cross shaft?(or a rail maybe) This is important since there is a wee bit of flexing when activating a knee lever. I feel a marked difference in the KL with and without the post. Alu is surprisingly strong and tough. I remember when testing my latest bell cranks. The arm on these measure 1/8" by 3/8" and look rather weak, especially since it has has 10 holes for the pull rod. I remember testing by putting a bell crank in the vise and hooking my digital scales to the outermost hole. I pulled it to 90 lbs with no sign of breaking or bending. The highest stress on a bell crank in the guitar is around 30 lbs

Hi Bent, Yes GFI does use a pillow block style center support according to these pictures. But only on the Utra's and not the Expo's. http://www.gfimusicalproducts.com/Pages ... atures.htm
As I mentioned in a previous post I do believe they now use steel cross-shafts though, but I am now venturing into sort of an unfamiliar territory because it has been several years since I had the S-12 GFI, and I will let others confirm or deny this statement.

LaVern