Center Joint gap

[Guest]

27 minutes ago, jacobsaunders said:

The centre joint you posted at the top of the thread, doesn’t exactly look as if it “worked” for you or anyone

What do you mean by that?

[Guest]

19 minutes ago, catnip said:

I think the reason for this is might be that the front end of the plane rides on a flat surface and the back end of the plane rides on very slightly lower surface since the blade has already removed a very thin slice from that area.  Also, I think the plane cuts more aggressively at the start of the cut than at the finish which may also add to this.  Just a thought.

That actually makes a lot of sense to me. Thank you for posting it.

[David Burgess]

"Take a look at 7:30 in this video. Rob probably is the most experienced person I can think of when it comes to planes.  He says that planes leave convex surfaces."

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They can, if one doesn't know the techniques for avoiding it.

At the beginning of the stroke, before the blade makes contact with the wood, you need to push down hard on the forward handle (which Rob doesn't appear to be doing on his cleanup cuts with the larger plane), and maybe even lift up a bit at the rear handle. When nearing the end of the stroke, do the opposite. Sometimes I'll even put my forearm on the back of the plane so the back can't rock up.

If the surface is already convex, take some light cuts out of the middle, and finish with a full-length cleanup stroke.

[Guest]

1 hour ago, David Burgess said:

"Take a look at 7:30 in this video. Rob probably is the most experienced person I can think of when it comes to planes.  He says that planes leave convex surfaces."

_________________________________________________________________

They can, if one doesn't know the techniques for avoiding it.

At the beginning of the stroke, before the blade makes contact with the wood, you need to push down hard on the forward handle (which Rob doesn't appear to be doing on his cleanup cuts with the larger plane), and maybe even lift up a bit at the rear handle. When nearing the end of the stroke, do the opposite. Sometimes I'll even put my forearm on the back of the plane so the back can't rock up.

If the surface is already convex, take some light cuts out of the middle, and finish with a full-length cleanup stroke.

That is good advice thats kind of what i do when i plane. I put all the pressure in the front handle of the plane a lot of pressure in the middle on both the front and the tote of the plane and at the end of the cut i basically just hold the front for allignment purposes and aply no pressure at all. I only push down the tote at the end of the board

[Guest]

UPDATE: I want to thank everyone who helped me make the joint as it should be. I finally made it today, I had to redo the joint many times and every time there would be a gap everywhere.  I thought it was my planing technique. Turns out it wasn't instead there was a more obvious reason, as to why the gap was still there. It was the glue. I was using a wrong recipe which should have been weight ratios and instead measured them by volume. Obviously hide glue doesnt have the same density as water and thus volume ratio isnt the same as mass ratio. What happened is the glue would be too thick and i also put a lot. So by the time I'd be ready to rub the two pieces together the glue would have already been gelled and thus the excess would not come out of the joint, creating a significant gap. I changed my recipe to 1:(3 1/2) glue to water w/w (weight : weight) ratio and also warmed my two pieces before gluing them. Not too warm, about 35 degrees celcius. Also i put less glue than i did before as I realised I was putting too much glue before. So when I did the joint properly this time the two pieces almost grabbed instantly I could barely move them. I only managed to move the upper piece a little bit forward and that was it. There was a suction the moment I touched them together.  It came out very nice with almost invisible gaps if not completely invisible. I should not that I did something a bit different though this time. I took a tiny 1 thou shaving with a 65 degree effective cutting angle block plane, I did measure it, over the whole surface except from the very ends. If anyone is insterested I can also upload photos from the results.

[Mark Norfleet]

Putting on a lot isn’t necessarily bad, and I would offer that too much is better than not enough as the increased volume of glue will extend the open time a bit.

As posted on MN recently, but maybe not in this thread...

https://www.yumpu.com/en/document/view/11427589/working-efficiently-with-hot-glue-the-strad

[Dennis J]

I have seen the video by Rob Cosman and I wouldn't argue with his conclusions. But there is no analysis of how the apparent high area is produced. Looking at your photos I would say that the gap only shows up at the end of the join. That does not suggest it is the result of a convex surface on one or both of the wedges because if that was the case the gap would extend further along the join toward the centre.

Anyway, however it comes about, taking a few short strokes in the middle before using a full length finishing stroke fixes the problem.

 

[Jim Bress]

13 minutes ago, Mark Norfleet said:

Putting on a lot isn’t necessarily bad, and I would offer that too much is better than not enough as the increased volume of glue will extend the open time a bit.

As posted on MN recently, but maybe not in this thread...

https://www.yumpu.com/en/document/view/11427589/working-efficiently-with-hot-glue-the-strad

I have a cheat sheet with David’s gel times for tasks taped to the wall next to my bench. I’m always surprised when the glue:water weight ratio is way off.  You’d think an ecologist would notice seasonal changes without the gel times suddenly changing. 

[Guest]

19 minutes ago, Mark Norfleet said:

Putting on a lot isn’t necessarily bad, and I would offer that too much is better than not enough as the increased volume of glue will extend the open time a bit.

As posted on MN recently, but maybe not in this thread...

https://www.yumpu.com/en/document/view/11427589/working-efficiently-with-hot-glue-the-strad

Anyway its done now and I really want to move on to the next steps, making the joint was a bit frustrating for me. Its probably that the joints where too cold when I warmed them a little it was fine. Also I checked that they still fitted well after heating them, because I was worried about warping. It was still fine.

[Guest]

36 minutes ago, Jim Bress said:

I have a cheat sheet with David’s gel times for tasks taped to the wall next to my bench. I’m always surprised when the glue:water weight ratio is way off.  You’d think an ecologist would notice seasonal changes without the gel times suddenly changing. 

Thank you, I had already found this article that Mr. @David Burgess wrote in the Strad. It was one of the reasons I thought that maybe there would be a problem with the glue gel time and the ratio as well. So this one really helped and I thank him for that.

[David Burgess]

20 hours ago, Jim Bress said:

I have a cheat sheet with David’s gel times for tasks taped to the wall next to my bench. I’m always surprised when the glue:water weight ratio is way off.  You’d think an ecologist would notice seasonal changes without the gel times suddenly changing. 

Thanks, but since most people will have not read the full article, and gel time of different glues varies, and also varies with different temperatures along with other conditions, I would like to emphasize that a "dry run" should always be performed and timed, and compared with the gel time of the glue under the same conditions.

[Guest]

1 hour ago, David Burgess said:

Thanks, but since most people will have not read the full article, and gel time of different glues varies, and also varies with different temperatures along with other conditions, I would like to emphasize that a "dry run" should always be performed and timed, and compared with the gel time of the glue under the same conditions.

Can I ask you a question, a dry run is performed on aluminum foil at least thats what I understood from the article. Why the aluminum foil? Why not use an offcut of the same piece of wood that you are going to glue?

[HoGo]

I'd guess the aluminum acts as heat sink and shortens the time for measurement. On wood you would have to wait longer and also every piece would suck some glue at different rate so aluminum foil makes the measurement more exact.

[Guest]

12 minutes ago, HoGo said:

I'd guess the aluminum acts as heat sink and shortens the time for measurement. On wood you would have to wait longer and also every piece would suck some glue at different rate so aluminum foil makes the measurement more exact.

But isnt the point of gel time to see how long it takes for the glue to gel on wood? Since thats what you are going to use it on. Just wondering... 

[David Burgess]

2 hours ago, Nestorvass said:

Can I ask you a question, a dry run is performed on aluminum foil at least thats what I understood from the article. Why the aluminum foil? Why not use an offcut of the same piece of wood that you are going to glue?

That can work fine too. The important thing is to measure the gel time,  compared to the time it takes to assemble the joint.

Measuring the gel time works well too for assessing the water dilution needed to make joints which are deliberately weak, such as when attaching plates to ribs. Much more predictable and repeatable than methods such as watching glue drip off a brush, or rubbing it between your fingers.

[Guest]

1 minute ago, David Burgess said:

That can work fine too. The important thing is to measure the gel time,  compared to the time it takes to assemble the joint.

Understood, thank you