At the end of this blog series I will post some measurements for those who want to build one and also some more photo details but for now I will go on to an overview of how I built the “works” of the chevalet.
This is my version of a blade clamping mechanism. I have limited metal working tools and capacity here in my AZ. shop so I kept it simple. I started with a piece of 3/8” square bar and a piece of 3/8” square tubing. I drilled and tapped the square tubing for a thumb screw (8-32 I think it was), then over-drilled a recess hole in the bar to keep the pieces together when the screw was loosened. Then by grinding away a little of the bar opposite from the screw, I made room for the blade. Next up I ground the square bar roughly round on the other end by hand on a bench grinder and threaded it for a 3/8” wing nut on one piece and a barrel nut on the other. The barrel nut threads into the handle knob.
Two square holes in the saw frame and you have a cheap simple clamp that works. I did beef up the saw frame arms later as they were too flexible.
On to the sliding mechanism. This is a shot of the adjustment tightener. It’s just a piece of 3/8” rod with it’s ends threaded, run through the center of the carriage base. The dado along the length of the bottom of the base locates it on the support post squarely. Square is very important on these parts if you are going to be able to square the blade to the work.
This is the basic carriage (again, my term) setup. The round bar made alignment a problem and will be refined later. The vertical ends each have a slot for the adjustment rod. The one on the front of the machine is vertical and the one on the back is horizontal. This was an early mock-up using 3/8” steel pipe for bushings.
The small wooden parts clamped to the bar are called “tumblers”. These are probably the most critical parts and are usually machined metal parts, but I’m not a machinist, I’m a wood guy
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This is the whole sliding mechanism mocked up with steel bar and pipe from HD. The saw frame is clamped firmly to the shaft and the shaft slides through the tubes. All you have to do to make the chevalet work is to insure perfect alignment of the two bearings. My, that was easy to say! Doing it may prove a little more of a challenge. Once tuned and with a little wax added, this setup actually worked reasonably well. You can also see the vertical adjustment slot in this photo.
When I received my linear motion bushings and precision shaft in the mail things really started to improve. As you assemble this piece and try the sliding motion it becomes very obvious that no wiggle at all is allowable. I started with a clamped together mock up and as I decided on correct positions and glued pieces up, one at a time, I could feel the improvement in sliding smoothness each time a clamp was replaced by glue. I always wondered why these were so massively constructed to do such dainty work. I think this is the answer.
The second last step in achieving the perfect alignment I needed was to make the bushings self aligning. I did this by over-drilling the mounting holes almost to the center but not quite.
Then when I assembled them I shimmed the clamps with washers so as to leave very little pressure on the bushings, allowing them to align with the shaft. The final clamping pressure was actually so light that I used narrow strips of double sided carpet tape to retain the bearings in the tumblers. It works, they align perfectly.
Try not to notice the cracks in the tumblers. ..over tension. The final step in wiggle elimination was to fill the square holes in the tumblers, where they fit over the square tubing with epoxy and reassemble them, square them to the tubing. and let the epoxy set for a rigid fit. I did wax the tubing first so that I can still disassemble it.
Here’s what the final setup looks like. It works just fine and I probably won’t change it because I want to work with the chevalet, not on it. That said it shows signs of being a prototype and could be done, knowing what I know now, a fair bit more tidily. The round rod didn’t give enough alignment control so I slipped a piece of square tubing over it and locked them together the same way as the blade clamps above.
There you go, you too can build a chevalet and have lots of fun making cool stuff with it.
Next entry, as I said above, I’ll try to give you some measurements and tell you what I might do differently if / when I build another one.
Comments and questions welcome.
Paul
-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/
20 comments so far
sras
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#1 posted 809 days ago
Another enjoyable blog Paul. I like to think that the time will come when I can tackle inlay work. I’m looking forward to seeing what new wonders you can now create!
-- Steve - Impatience is Expensive
rivergirl
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#2 posted 809 days ago
What is this for and what would you do with it? Sorry- I’m clueless. Nice pics though. :)
-- Homer : "Oh, and how is education supposed to make me feel smarter? Besides, every time I learn something new, it pushes some old stuff out of my brain."
shipwright
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#3 posted 809 days ago
rivergirl See this blog: http://lumberjocks.com/shipwright/blog/series/3746
It should explain what it does.
Thanks
-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/
rivergirl
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#4 posted 809 days ago
I will check it out. Thanks!
-- Homer : "Oh, and how is education supposed to make me feel smarter? Besides, every time I learn something new, it pushes some old stuff out of my brain."
HorstPeter
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#5 posted 809 days ago
A big thank you for this. Maybe I’ll dare build myself one too sometime. Although right now I wouldn’t know where to put it without causing me more trouble than joy I’m afraid.
Dennisgrosen
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#6 posted 809 days ago
thank´s for a great picture book :-)
I have no trouble following the build but I have a Question to it
since my Brain isn´t the sharpest in the drawer
why is there two axels cuoldn´t one bee enoff to slide on
and is there an advance in it to have two vers. one
take care
Dennis
shipwright
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#7 posted 809 days ago
Thanks everyone.
Dennis, I imagine that there were advances and developments when it was first introduced but this is pretty much the standard design that I’ve seen and represents what they have looked like for about 200 years. The two shafts joined by the tumblers is, one can only presume to afford you the ability to move the saw a little bit laterally (left or right). In use it becomes obvious that this is a great advantage especially in sawing curves.
Horst, By removing the bottom two bolts it can be stored in a little less space, but I agree it’s a bit bigger than a scroll saw.
Thanks again.
-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/
BigTiny
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#8 posted 809 days ago
Hi Paul.
Nice to see folks today keeping the traditional methods and tools alive.
Is this based on the ones in the Boule school in Paris? It looks much similar.
Paul (not you, the other one)
-- The nicer the nice, the higher the price!
Dennisgrosen
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10854 posts in 1286 days
#9 posted 809 days ago
Thank´s , the curve explanation I can buy :-) makes alot of sence
when you don´t need to move the piece all the time and it just hit when
I write this that it goes for the straight sawing too …. thank´s paul for being a patience teacher :-)
take care
Dennis
shipwright
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3399 posts in 969 days
#10 posted 809 days ago
Paul (not me, the other one), Yes it’s based on photos and write ups I found online and they are the original parisian Chevalet de marqueterie that is used in the boulle school. My main photographic aid was Yannick Chastang’s site here: http://www.yannickchastang.com/tools/Marquetry+donkey/ plus the short grainy video on Patrick edwards’ blog here: http://wpatrickedwards.blogspot.com/2010/09/chevalet-video.html. They both studied there I believe and Patrick’s machine in the video is a genuine antique.
-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/
Mathew Nedeljko
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462 posts in 2000 days
#11 posted 808 days ago
Paul, I also believe that Patrick Edwards chevalet is pretty much taken straight from the plans shown in Pierre Ramond’s book Marquetry. Your’s is very similar, and certainly looks like it cuts equally well.
I’m not sure I quite understand how drilling the holes for the linear bearings almost to the center of the tumblers helped make the bearings more self aligning? I would have thought that you wanted a good solid contact between the tumblers and the bearing with no room for play whatsoever. It looks like what you found though was that you needed only slight pressure on the bearings to allow them to slide easier?
Could you please provide some details on the bearings and precision shaft you used?
Mat
-- You either think you can, or think you can't. Either way you are right. Henry Ford
shipwright
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3399 posts in 969 days
#12 posted 808 days ago
I’ll look up the bearings in the morning. The holes almost to the middle- It allows the bearings to tip a little in the holes while still being wiggle free at the center. It’s because without accurate machine work it’s pretty well impossible to get the actual holes lined up perfectly. Am I explaining it? It’s not about pressure on the bushings.
-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/
Dez
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#13 posted 808 days ago
Very Cool! Much appreciated!
-- Folly ever comes cloaked in opportunity!
BigTiny
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#14 posted 808 days ago
As I mentioned elsewhere, Ronaldo over on www.thomasjmacdonald.com is a student at l’echole de Boulle in Paris. He would be tickled pink to see this chevalet of yours. Maybe you could drop in there some time and post it for the guys there?
Paul (the Winnipeg one)
-- The nicer the nice, the higher the price!
shipwright
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3399 posts in 969 days
#15 posted 808 days ago
I just signed up Paul. I’ll check the site out tomorrow. I’m on two forums now… that may be enough…. or maybe too many.
-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/
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