Over the last few days I have been building 6 necks for a next batch of electrics.


I purchased 4 of Stewmac's #4401 carbon fiber re-rods a while back and more recently purchased 8 of LMI's GR4 carbon fiber re-rods.


4401 vs. GR4 consumer report:


The GR4s were not of consistent thickness. Out of the 8 GR4s 5 were between 0.133" and 0.138" thick which meant sanding them (very dirty job, toxic without a mask, and very easy to get nasty slivers). My main concern was that the GR4 were all slightly warped along the plane that would produce (unwanted) relief or back-bow betweeen 0.004" and 0.016".


The 4401s were all consistent length, thickness, were not warped, the downside being they're slightly more expensive (a quantity of 8 at $12.59 per vs. the GR4 at $10.30 per which can add up).


I mentioned these issues to LMI's customer service dept in an email. I received a reply stating LMI considers a variance of 5 thousandths to be well within acceptable tolerances for this material and typically do not get complaints about it. The (unwanted) relief issue was not addressed and I think .138" is more like .013" variance (doesnt fit the .125" channel).


Are there alternate sources for carbon fiber reinforcement rods out there?





Tags: 4401, Carbon, GR4, fiber, neck, reinforcement

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Ive used these guys before, but I confess I havent measured the rods or checked for inconsistencies.

We use structural poltruded unidirectional carbon fibre rectangular sections for our neck reinforcements - and while it doesn't seem to vary more than a .001 or so it still comes with an advertised ( + or -) .005 tolerance. The warp you have is probably unacceptable from a specification angle but our rod/bars are not tensioned into the slot (we give it some clearance in the vertical plane) and we let the epoxy fill any gaps and self level in the slot - I wouldn't worry about that. Clamping the rods tightly into the machined slots while gluing is inviting a neck twist if they are out of spec.

To elaborate on this process we used a dead flat caul to snug the rods into the neck and a liberal dose of West System to fill the channel and glue the rods in, this way the neck and bars are jigged dead flat and any gaps are filled with epoxy thereby reducing the possibility of resonance and vibration. We leave a fillet of epoxy on top of the rods in the channel and then scrape the neck/fingerboard surface clean for toothing and subsequent fingerboard placement. Having the rods flush with the surface makes it difficult to clean up this surface and wear the tools as well - better to leave a lick of epoxy than a carbon fiber speed-bump.

The thickness issue is however, totally unacceptable if you are machining with a .125 bit and you should return this rubbish in future.

However, on a similar note - to compare product experience - I've just used a new circular fret saw from LMI (90 tooth) with CMT blade stiffeners (lot cheaper than the LMI ones) and have to say it is a very good unit. I have previously used the Stew Mac circular blade but they are hard to keep true and the teeth are somewhat prone to bending - don't want to bump/drop these units. The LMI blades are also a lot thinner at the boss which means that the blade stiffeners will fit on a normal arbor without running out of arbor length (stiffeners add a 1/4 inch to the blade pack depth). Not to criticise - they are both good units compared to struggling with a fret saw - but my vote is with the LMI unit (providing you have blade stiffeners).

Customer relations is a work in progress for most organisations - "not getting complaints" can mean two things - one good - one bad! Just tell them it is unacceptable and get them to pay for the return and reship - these are your rights.

Hope this helps , Rusty.
Thanks so much for hitting me with I will try them out as their prices are the best. I'll post the final verdict here when I get around to it (hopefully within 6 months).

Thanks for the reply, I am normally very happy with quality from either LMI or Stewmac, I believe this is the first time that I've felt that the LMI quality control let me down.

That is very similar re-bar installation method to what I have cooked up over here. Are you self employed Rusty? or factory employed?

Thanks again for responding


Hi Sean,
Private business, Myself and my son - servicing the top end of the industry for ten years and looking after a number of the large city shops and clients across the country. It's a lot of fun and good work. Rusty.
Try Jim Watts at Los Alamos Composites.


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