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Oversize button guidepin holes in the action board


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I am working on a 20 key Lachenal at the moment.... the buttion guide pin holes seem very worn so that the buttons are sloppy; some are oval and chipped away at the top and almost all are around 4.2mm diameter, whilst the guide pins on the buttons are 3mm. I am thinking of filling the existing oversized holes with a hard setting wood filler and then redrilling 3.3mm guide holes.

 

Any advice, please; Dave Elliott's excellent book is silent on this subject!

 

Thank you

 

David

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I am working on a 20 key Lachenal at the moment.... the buttion guide pin holes seem very worn so that the buttons are sloppy; some are oval and chipped away at the top and almost all are around 4.2mm diameter, whilst the guide pins on the buttons are 3mm. I am thinking of filling the existing oversized holes with a hard setting wood filler and then redrilling 3.3mm guide holes.

 

Any advice, please; Dave Elliott's excellent book is silent on this subject!

 

Thank you

 

David

 

Completely non-trad.....I'd thread in nylon (or delrin) setscrews and redrill them...I hate those wood fillers.......

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I'm not much one for using normal wood fillers. Most of the time when woodworking and I need to fill in a hole or ding I just mix some fine sawdust with wood glue. You can make this as thick or thin as you like and it dries nice and hard if you use a good glue like tight bond.

 

-Lep

 

If the key height is set right: so the tip of the key's peg is well located into the guide hole, the key's cross bushings are good, and there is not too mush 'slop' between the key and the hole in the action box cover, the 'oversize' of guide hole is no great issue.

 

If you truly wish to screw up the action, fill the guide holes, and try to re drill them on an exact pitching to match the key hole axes both in location and alignment (whilst maintaining action lever arm orientation). When the inevitable occurs (which it will without some tooling like guide bushes and jigs) and there is misalignment between key hole, the lever arm position, and the action will just lock up and not work. The key's will jam, and the key pressures will become variable. You, perhaps may have access to a fully tooled workshop, and be able to control all the variables, if so I would advise a clearance of around 1 mm on the diameter as the guide pins need a fairly sloppy fit to accommodate wood movement etc.

 

My advice is to get the key hole bushings (if any) in good condition, similarly the key cross bushings, and then with good pads set the action height and travel correctly. The 'worn' guide pin holes will look after themselves. I can assure you that 1 mm peg clearance is not an issue. The cause of the ovality and chipping how ever is! The cause is that the action has been set up incorrectly, too high, or cross bushings have been lost.

 

The manual is silent on this point, simply because it is not a job that needs doing, certainly not as a maintenance function. To be honest, I don't think I would include it in the restorer's manual that I am planning. but I would take advice on that. When I have had action plate damage I have inlet wood squares with the grain of he correct orientation, and dealt with the one or two guide pin holes that are affected -only.

 

Dave E

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Completely non-trad.....I'd thread in nylon (or delrin) setscrews and redrill them...I hate those wood fillers.......

These synthetic plastics should also provide less friciton and binding thn the original wood (or a mix of glue and sawdust).

If you could get Teflon screws, get even less friction.

--Mike K.

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If the key height is set right: so the tip of the key's peg is well located into the guide hole, the key's cross bushings are good, and there is not too mush 'slop' between the key and the hole in the action box cover, the 'oversize' of guide hole is no great issue.

 

My advice is to get the key hole bushings (if any) in good condition, similarly the key cross bushings, and then with good pads set the action height and travel correctly. The 'worn' guide pin holes will look after themselves. I can assure you that 1 mm peg clearance is not an issue. The cause of the ovality and chipping how ever is! The cause is that the action has been set up incorrectly, too high, or cross bushings have been lost.

 

 

Thanks, David. Exactly the advice that I sought.... do nothing! The cross bushings and the key hole bushings are in poor condition and the keys are very sloppy on the action arm, which probably accounts for the chipping around the hole.

 

Thank you for your most helpful post.

 

Best wishes David

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Exactly the advice that I sought.... do nothing! The cross bushings and the key hole bushings are in poor condition and the keys are very sloppy on the action arm, which probably accounts for the chipping around the hole.

Yep, sounds like Gerald Haugh's Jeffries, which I was working on last week - all I did was to replace the missing bushings, and now his buttons don't stick...

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