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Is the glue the wood or the guy holding the tool????

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Forum topic by Kevin Wells posted 08-11-2013 10:37 PM 1079 views 0 times favorited 21 replies Add to Favorites Watch
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Kevin Wells

28 posts in 492 days


08-11-2013 10:37 PM

I have been attempting a board to bowl project (one I’v done several times before) using a 10×10” piece of 3/4 Bubinga. The first two times I attempted this, I used CA glue to mount a waste block (mdf). The moment the gouge touched the Bubinga, the board separated from the waster block. Several folks reminded me that CA did not have the shear strength for this application and to use a Tightbond product.

So this week, I glued a new waste block on (cedar scrap) using tightbond II. I cut three rings away. As I started the fourth, The Bubinga separated from the cedar waste block.

I had sanded off all the CA residue, prior to gluing with Tightbond II. The Tightbond is only about a month old. I’v frequently used Bubinga in glue ups with segment work so I’m kind of at a loss here. Any thoughts?

Kevin

-- Kevin, Chuckin' Wood, http://chuckinwood.com


21 replies so far

View Gary's profile

Gary

7229 posts in 2086 days


#1 posted 08-11-2013 10:48 PM

Just curious, Kevin…how long did you let the glue cure?

-- Gary, DeKalb Texas only 4 miles from the mill

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kdc68

1979 posts in 930 days


#2 posted 08-11-2013 11:05 PM

Could it be the natural oils and resins in the Bubinga be the issue here ? If so, prior to glue up wiping the wood with acetone might work here ?

-- Measure "at least" twice and cut once

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Gary

7229 posts in 2086 days


#3 posted 08-11-2013 11:17 PM

Kevin…....Oh Kevin…...HEY KEVIN…..
How long did you let the glue cure?

-- Gary, DeKalb Texas only 4 miles from the mill

View rrww's profile

rrww

263 posts in 766 days


#4 posted 08-11-2013 11:33 PM

Like kdc68 said- try wiping down with acetone then titebond over night it should work.

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Dallas

2905 posts in 1140 days


#5 posted 08-11-2013 11:40 PM

look at the wood joint, see what broke. The glue is usually stronger than the wood.

-- Improvise.... Adapt...... Overcome!

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Kevin Wells

28 posts in 492 days


#6 posted 08-12-2013 12:44 AM

The glue cured for 18 hours before turning (after the previous week failure I wasn’t taking any chances). As far as the joint, both the waste block and the bubinga are intact. The only thing that seemed to have broke was the glue itself. There was glue residue on about 2/3rds of the waste block and about 1/3 of the bubinga (within the spot where glue should be) I had applied the glue to both pieces and used a 10 pound weight to clamp it (all my clamps were elsewhere).

K

-- Kevin, Chuckin' Wood, http://chuckinwood.com

View Gary's profile

Gary

7229 posts in 2086 days


#7 posted 08-12-2013 12:51 AM

You are suppose to wait 24 hours for titebond to cure before putting stress on it. If it had cured, the wood would have given before the glue. It wouldn’t hurt to hit it with a little naptha or spirits prior to gluing, then let it set for 24 hours..

-- Gary, DeKalb Texas only 4 miles from the mill

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Dallas

2905 posts in 1140 days


#8 posted 08-12-2013 12:53 AM

Hmmmm, He said! And repeated, Hmmmm!
A glue joint is stronger than the wood, even with the hardest woods.

I haven’t worked with Bubinga, but I believe, (I’m not certain), that it is not that oily. It could be, I only work with domestic woods like the cedar, therefore, the weakest link has to be the Bubinga.

Wipe it down with acetone after sanding it rough. You don’t want a slick surface for glue.

Try that and get back to us.

-- Improvise.... Adapt...... Overcome!

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Kevin Wells

28 posts in 492 days


#9 posted 08-12-2013 01:16 AM

@ james, no edits. The tightbond was gluing a cedar scrap wasteblock.
Originally when I used the CA it was with MDF.

I’ll try the acetone and let you know :)

K

-- Kevin, Chuckin' Wood, http://chuckinwood.com

View Gary's profile

Gary

7229 posts in 2086 days


#10 posted 08-12-2013 01:22 AM

Kevin, don’t forget to wait 24 hrs. I believe even the bottle says that. Watch your clamping pressure too. You don’t want to squeeze all the glue out. Doesn’t need to be all that tight

-- Gary, DeKalb Texas only 4 miles from the mill

View Wildwood's profile

Wildwood

1035 posts in 787 days


#11 posted 08-12-2013 01:16 PM

Bubinga an oily wood so wiping down mating surfaces with acetone before applying glue helps. If getting glue failures after wiping down with acetone not sure changing glues will help. Even five-minute epoxy takes 24 hours to fully cure.

I might try scuffing up mating surfaces with sand paper, wipe down with acetone, glue and wait until glue fully cures before attempting to turn.

-- Bill

View PurpLev's profile

PurpLev

8476 posts in 2301 days


#12 posted 08-12-2013 01:27 PM

as mentioned, before putting stress on glue joint allow 24 hours to dry.

that said – your comment about both waste and bubinga still in tact sort of suggests that the glue did not penetrate deep enough and cured to allow for these 2 elements to bond together. it may be that the CA or the natural oils in the bubinga are preventing this from happening – use acetone or mineral spirits to wipe off the bubinga real good (with emphasis on the ‘real good’ part) and reglue. allow 24 hours to dry (I would give it even more if you’ve experienced some weaknesses already) then try again.

Another thing to try since you notice that the force applied here is large enough to cause glueup issues is take a 2nd ‘waste block’ and put it at the other end of the bubinga (unglued) – then pin the tailstock with a live center in it against it and apply some pressure. this will create some friction pressure against the bubinga from the tailstock side which will help reduce the amount of the side forces applied by your turning tools which currently only the headstock/glueup are facing and have to stand up to.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

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Bluepine38

2876 posts in 1738 days


#13 posted 08-12-2013 03:18 PM

I agree with PurLev on the tailstock block, I used that trick when I was making bowls from a blank using
a cross slide rest for parting the wood and it helped considerably.

-- As ever, Gus-the 75 yr young apprentice carpenter

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RussellAP

2950 posts in 939 days


#14 posted 08-12-2013 03:34 PM

What you need is one of those 6” HF faceplates and some thick double sided tape. You can see it coming apart before it does and perhaps catch it, but mostly if you get a good clean seal it will stay put. That’s an awful large piece to turn unchucked though. I’d consider something more conventional.

-- A positive attitude will take you much further than positive thinking ever will.

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johnstoneb

688 posts in 826 days


#15 posted 08-12-2013 04:06 PM

I don’t think a 10 lb weight is heavy enough to get a strong glue joint. that is 10 lbs spread over a large area(ie. 3”x3” is 9 square in divided into 10 comes out to 1lb per square in force, not near enough for a good strong glue joint. A larger piece will give even less clamping force.) Try trying gluing both pieces, separate with a piece of paper and clamp for 24 hours. You should get good mechanical strength in the joint and the paper will allow you to separate it without damaging the wood. I just read your other post. I am not sure western red cedar has the strength needed to handle the centrifugal forces. I would use a doug fir, yellow pine or hardwood for the backing block

-- Bruce, Boise, ID

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