Morris Chair


bleedinblue

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Yeah Chet, I understand that if the arc is cut in a single line the radii will be different once the inch thickness of the lamination is added, but I think Drew and I both made two cuts... Using thr template to essentially cut the one inch strip out.  I should have taken a picture before cutting, I'm sure I'm not describing it properly. 

Regardless, I had a good bit of shop time today.  The bending form is done and the blanks for the arms are flattened, square and ready for re-sawing. 

I ripped the arm blanks wide, around 7 inches.  With only a 6 inch jointer, that left me removing the pork chop and leaving the extra one inch or so heavy.  Easy cleanup with the jack plane.  This has become pretty normal work flow and works great for me in most applications.

I didn't have as much cork as I thought for the bending form, but I had a lot of thin sheets of foam.  I think it'll work just as well. 

 

 

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Now on to the re-sawing.  I followed Marc's instructions, set the saw for the drift and my test pieces came out too far off.  I'm going to re-set the fence to square and do some more testing before going for the real thing.  I also need to try out the re-saw bar to decide if I'm going to use that or just go fence only.

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Run a trial run with an arm and leave it clamped for a bit to compress the foam down before the real deal. It would be unfortunate if the foam compressed and the whole setup lost needed clamping pressure. Also like i said before make sure to coat every bit of the surface if your using epoxy.

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I just got both arms sliced up.  The first arm went really well with no problems at all.  The second arm, for some reason, gave me some problems.  I'm not sure why but I seemed to have some drift issues I didn't have with the first arm.  I think I maintained enough thickness though, I'll know more when I have a couple hours to stare at the drum sander. 

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Before my drum sander shot the craps, I got one arm cleaned up and put into the bending form as a trial run.  Even on the arm that gave me trouble during the re-saw, thickness wasn't a problem.  My goal was one inch thick arms and I'm still fat of that, somewhere between 1 1/16th and 1 1/8th.  Clamping down the bending form was pretty nerve racking, I kept waiting to hear a huge crack.  I was going off faith that the laminations were thin enough to bend to the relatively shallow curve.  All good. 

I left the arm clamped in the form to help compress the foam, like Nut said.

I do intend to drill more holes in the form for the clamp heads.  They're not really necessary, but it was nice just dropping the f-style clamp head in the hole and not having to worry about it sliding around on me.

But alas, this project is on hold until I fix my sander.  Of all the tools in my shop I'd expect to fail me, that wasn't one of them.

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  • 4 weeks later...

Back in business after the Supermax calamity. 

I just got an arm glued up.  I think all went well, but I obviously won't know until I pull it from the form and get it cleaned up. 

I used totalboat crystal clear, which by my research should be identical to WS 207.  I started off applying with a paint brush, but that was so slow I switched to an ink roller.  

I had cut the top of the form into thirds instead of the bunches of sections Marc did.  During clamp up, two of the three sections split down the middle. Hopefully that doesn't bite me, time will tell. There should be a whole lot of pressure still applied, so I *think* it should be OK. 

 

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It seems to me like if I cut it into smaller sections those sections will be weaker...or maybe they'll have more individual give and be allowed to flex more...I'm not sure.  The back end of the arm has a veerrrrry slight cup to it.  Clearly the breakage has reduced the pressure on the middle and allowed the bow.  I'm itching to get it out of the clamps to see but I'm going to give it at least 24 hours.

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12 minutes ago, bleedinblue said:

It seems to me like if I cut it into smaller sections those sections will be weaker...or maybe they'll have more individual give and be allowed to flex more...I'm not sure.  The back end of the arm has a veerrrrry slight cup to it.  Clearly the breakage has reduced the pressure on the middle and allowed the bow.  I'm itching to get it out of the clamps to see but I'm going to give it at least 24 hours.

I'm with you and don't think smaller sections are going to solve this. It appears to me that the plywood failed not your glue line of the plywood, is that correct? If that's the case I would either clean both sides up and glue it back together or get some MDF and remake the top section. Unfortunately I suspect you are right about the pressure in the middle.  

Edit. Actually the more I look at the pics it almost appears that the clamps may be too close to the edge and since the arm is about 3/4" in the clamp pressure twisted it off versus applying pressure straight down. The good news, if that's the case, is fix what you have and just move the clamps in further on the next one.

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I agree with Paul on the above clamps being a bit too far toward the outside. You should be able to glue that ply back together and still be able to use it. At the absolute worse keep a clamp across it holding it form splitting apart. I think you should be good with the arm that is in there. If it doesn't turn out i urge you to make another arm this project is just too awesome to do things half right.

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Yeah, my basic plan is to jam a bunch of epoxy into the split to repair it, then take steps to get my clamps further toward the middle for the next arm.  I think it'll work fine.  My original visualization was that it was OK to have most of my pressure toward the outside of the arm, since that's where I really need perfect glue lines.  I guess I now see why that's not 100% accurate, lol.

I think this arm will turn out OK, and if it doesn't I don't think it'll be because of the split form.  The cupping, at least the cupping I can see, is extremely minor.  As of now, I'm not stressing about that.

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25 minutes ago, pkinneb said:

Edit. Actually the more I look at the pics it almost appears that the clamps may be too close to the edge and since the arm is about 3/4" in the clamp pressure twisted it off versus applying pressure straight down. The good news, if that's the case, is fix what you have and just move the clamps in further on the next one.

Now that I look at it again, I believe what Paul said is correct about the clamp placement and this causing the failure.

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I went downstairs to go do the hot tub chemicals, got too close to the shop, and couldn't resist pulling the clamps off.  No time to do any cleanup work, but I think the arm looks just fine.  Very little spring back, and the cupping can't be seen until you lay a straight edge across it. 

I'm still somewhat nervous about the glue lines being visible, but I won't know that until I get the edges cleaned up on the jointer, and that probably won't happen until Saturday. 

As of now, I'm a happy camper though. 

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I bought these guys and do my gluing with epoxy on top of them. After cure the epoxy just pops strait off as does regular pva glue.

https://www.amazon.com/gp/product/B011R32JDY/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Too late now but maybe in the future. Also i know you mentioned you weren't going to bent lam the back slats but after all the work i did trying to scrape and sand the bent lam back slats i couldn't imagine the amount of extra work needed to clean up band saw cuts. I think the bent lamination is the better way to go. Also making the form gives you a good place to clamp the slats for sanding and scraping.

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