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Author: Subject: Old Project - New Lute
jdowning
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[*] posted on 9-1-2008 at 12:28 PM


With the plane repaired, tested and back in commission, blade razor sharp and the throat set to minimum gap, the remainder of the first test batch of eight ebony fillets was completed. Apart from the first two fillets, the thickness of the remainder was held to a consistent 0.035 inch, +/- 0.001inch (0.89 mm) using the plane. A satisfactory result. The first two fillets showed a slightly wider variation in thickness (undersized to 0.003 inch maximum) - due probably to using a scraper blade for the final cuts, which results in removing too much material in places. Only the plane, which provides much better control, than the scraper blade, will be used in future.
The depth of each fillet was reduced to about 2 mm using the same process i.e. using the thicknessing block and plane. The objective here was to remove all traces of saw marks and produce a smooth finished edge (as well as a uniform depth). Any remaining saw marks might act as a stress concentration point that could induce splitting of the brittle ebony during hot bending.
Some scrap ebony fillets from this batch were used for preliminary hot bending tests.
My new, electrically heated bending iron (see 'Waste not Want Not" on this forum) is provided with slots for bending the fillets. The slots are designed to support the sides of the fillet during bending - to minimise 'buckling' of the fillet and to provide a better heat distribution on both sides of the fillet in order to facilitate the bending process.
An adequate curvature of the test fillets was achieved by this means. However, I am not happy with the new bending iron as it is 'under powered' and needs a higher wattage heating element. Warm up time of about 30 minutes was too slow and bending of the fillets was also very slow. Insufficient heat may cause 'forcing' of the work and result in breakages. Also this bending iron is only 2.5 inches (64 mm) in diameter - which is a little on the small side).
I have, therefore, decided to modify my propane heated bending iron to provide slots for bending the fillets. This bending iron is fast to heat up, easy to control and has a quick heat recovery. Also the heating surface has a diameter of around 4.5 inches (115 mm) which will allow better heat distribution, a more uniform bend and , consequently, reduce the risk of fillet breakage (hopefully!).
As a result of these tests I shall proceed with my plan to use ebony inter rib fillets.



Fillet Bending comp (638 x 825) (464 x 600).jpg - 55kB
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Jameel
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[*] posted on 9-1-2008 at 04:51 PM


Nice progress John. Thanks for taking the time. Sorry to hear about your plane. I've done that a couple times. So I covered my concrete floor with wood. I would NEVER work on concrete again. Stanley 60/12's are nice planes. I never much liked the cam lever. The big diameter wheel on my Lie-Nielsens will spoil a guy.



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jdowning
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[*] posted on 9-2-2008 at 03:36 AM


I think that replacement of the cam lever with a screw is an improvement - adjustment is a bit easier - and it is working out well so far.

I hope that the updated current version of the Stanley 601/2 plane is better made than the one I have. There are similar planes on the market at 1/3 the price of the Stanley (and without the cam lever!). Made in India as I recall. They likely require some fine tuning but at under $20 should be a good deal for those seeking a low cost plane. Must take a closer look at one next time they come on sale.

I suspect that the plane would have broken in this manner even if dropped on a wooden floor as it landed on its back so the brittle, grey cast iron cam lever took an impact sufficient to break it.

Don't go dropping that Lie-Nielsens !!
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ALAMI
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[*] posted on 9-2-2008 at 06:36 AM


John, I'm glad you're safe and sound after that plane crash !

Please guys, be careful.
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[*] posted on 9-2-2008 at 07:14 AM


John. if you need one I have an extra cam lever from an antique 60 1/2.
I got it off of e-bay but the mouth of the plane had been filled badly so I ended up using it for the blade only. the rest of the plane is pretty much useless but its good for parts!
anyways your on my way to montreal which I am going next week.
I could always drop it off.
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jdowning
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[*] posted on 9-2-2008 at 11:48 AM


Nice one ALAMI - this woodworking game sure is a dangerous business!

Thanks Samir - the modification of my plane is irreversible so I cannot now replace the lever cam. However, if you have time en route to Montreal next week why not break your journey here for a spot of lunch, a chat and to 'compare notes'? You are most welcome - and bring the 'dud' plane as well - to see if it can, in anyway, be refurbished and given a new lease of life.
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[*] posted on 9-2-2008 at 11:59 AM


ok will do.
I will let you know by mail what is the plan.
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[*] posted on 9-3-2008 at 11:59 AM


My 'heavy duty' propane heated bending iron has now been modified to prepare for bending the ebony, inter-rib fillets.
The heating surface of the bending iron is a piece of thick walled (3mm thick) seamless brass tubing that has been formed into an oval section by squeezing it in a vice.
The channel, designed to support the fillets against buckling during bending (they are 0.9 mm thick by about 2mm wide), was made in two parts from 3mm thick copper. The first part - about 12 mm wide - was formed to match the curvature of the heating surface by hammering on a tinsmith's anvil (an iron tube or round bar would have done just as well). The inside edge was then filed flat and square and the piece rivetted to the end of the heating tube with three copper rivets.
The other part of the channel was made about 22 mm wide, formed to the curvature of heating tube and the inside face made square and straight to match the fixed component. This part is adjustable - held in place by two brass screws - the heating tube being drilled and tapped to accommodate the screws. The screw slots allow the gap in the channel to be set from zero to about 8 mm. This will allow the fillets to be bent either singly or in bundles.
The attached images show the modification prior to filing and final finishing of the outer surfaces - a purely cosmetic operation but I have my pride!



Modified bending Iron comp (523 x 799) (393 x 600).jpg - 49kB
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[*] posted on 9-6-2008 at 11:40 AM


The modified propane heated bending iron is now re-assembled and ready for testing.

The 'average' profile of a fillet was transferred from the mold using a draughtsman's "Flexicurve" (In practice each fillet profile will be different due to the flattened section of the bowl). The curve was marked onto a piece of pine, cut out on a bandsaw and smoothed to form a jig for the fillet profiles.
The small nails around the edge of the jig were intended for holding the fillets against the jig using elastic bands - in order to retain their shape after bending. However, I do not think that this will now be necessary - just an added complication.
Three of the prepared fillets were held together as a bundle for testing (with masking tape applied at the extreme ends) and the gap adjusted in the bending channel to just fit the width of the bundle. Bending three fillets at one time should be faster and provides some extra stability to the thin, deep fillets during bending. The edges of the fillets were examined for any flaws or saw marks that might act as stress raisers and result in breakages during bending. The idea was to position these flaws on the inside curve where the wood would be subject to compressive loads and be less likely to fail during bending. However, after messing around with the tape and other preparations, I still managed to end up with some flaws on the exterior of the bend - the worst case scenario! Also, a slight grain 'run out' was noted in the fillets which will not help either!

After bringing the bending iron up to temperature (about a minute) bending commenced - matching the curve bit by bit against the jig to obtain the required profile. Despite the concerns about possible breakage there was no problem in hot bending the fillets - although a bit of practice is going to be necessary for best results.
Despite having the support of the bending channel side walls, some slight sideways buckling of the fillets did occur in places. However, it is judged that there is sufficient flexibility remaining in the bent fillets - both laterally and longitudinally - to allow precise matching of the rib profiles when the fillets are finally glued in place.



Fillet Bending Test comp (600 x 394) (600 x 394).jpg - 54kB
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