Sound post patches, what shape?

[Mark Norfleet]

This is my approach to reducing stress risers at the ends of cleats.   This shape is also very useful when reinforcing cracks that are close together.  I’m clearly not in complete agreement with Michael’s comment from the recent chest patch thread that patches should have clean sharp edges. In this case, I did some regraduating after the patch was in.  The photo was taken before I had completely finished and cleaned things off etc.

[Jeffrey Holmes]

28 minutes ago, Mark Norfleet said:

This is my approach to reducing stress risers at the ends of cleats.   This shape is also very useful when reinforcing cracks that are close together.  I’m clearly not in complete agreement with Michael’s comment from the recent chest patch thread that patches should have clean sharp edges. In this case, I did some regraduating after the patch was in.  The photo was taken before I had completely finished and cleaned things off etc.

That's pretty much the standard cleat shape I now use.  60 degree angle at the ends.  Jerry's shop uses something very similar...  I leave a little more in the center than you do, I believe. When things (cracks) get close, I also may alternate diamond shaped cleats (with the grain running off at about a 45).

 

[Mark Norfleet]

I usually leave more in the center too.

heres another shape I use.  I think the ends are all at 45 degrees.

[Jeffrey Holmes]

18 hours ago, Mark Norfleet said:

I usually leave more in the center too.

heres another shape I use.  I think the ends are all at 45 degrees.

Some (especially the ones in the center) look a little like bats!  Cool!

 

[DuffersEdge]

On 3/27/2020 at 11:02 PM, Jeffrey Holmes said:

That's pretty much the standard cleat shape I now use.  60 degree angle at the ends.  Jerry's shop uses something very similar...  I leave a little more in the center than you do, I believe. When things (cracks) get close, I also may alternate diamond shaped cleats (with the grain running off at about a 45).

 

They look very elegant indeed.  

Please forgive what may be a naïve question, but were those cleats pre-shaped like that prior to hide gluing? If so, were they clamped in place during the glue drying period?

As a complete novice (but learning and trying to put into practice so much on this forum) I have a little fiddling to do to get the clamp on a completely flat topped cleat. So I have taken to gluing them on quite thick, with flat tops, taking the clamps off after some 24-48 hours from gluing, and then carving the cleats down quite considerably once glued, thinning even more toward their edges.

[Andreas Preuss]

Maybe a little late to join the conversation.

I came across the idea of making patches with straight sides first when readings a copy of the Weisshaar book. (I think it was back then in 1989) I neither could understand the reason doing so. 

However i made a few of those and found it a sort of time consuming to cleanly fit the corners of the patch. 

So now I think oval patches are just best with even curvatures in all directions. It's most time efficient too.

However often I am asking myself if most sound post patches aren't too big for what they are supposed to hold together. Once I made a 2 layer patch where the inside was cross grain and the outside along the grain to minimize the size. 

[Jeffrey Holmes]

2 hours ago, DuffersEdge said:

Please forgive what may be a naïve question, but were those cleats pre-shaped like that prior to hide gluing? If so, were they clamped in place during the glue drying period?

I make a block profiled to the shape and size of the cleats I plan to use, chalk fit the gluing surface, split the individual cleat off slightly thicker than what I plan to be the finished thickness, glue and clamp in place, then shape with a flat-ish gouge.

Jerry Pasewicz's shop (Triangle Strings) employs a similar procedure and has a step-by-step description of the process (for one of the cleat shapes) online and available here.

36 minutes ago, Andreas Preuss said:

I came across the idea of making patches with straight sides first when readings a copy of the Weisshaar book. (I think it was back then in 1989) I neither could understand the reason doing so. 

However i made a few of those and found it a sort of time consuming to cleanly fit the corners of the patch. 

So now I think oval patches are just best with even curvatures in all directions. It's most time efficient too.

Interesting... I find the reverse to be true. I think we tend to adjust working methods to favor what we're used to doing, and therefore become more efficient at accomplishing the task.

[Brad Dorsey]

1 hour ago, Andreas Preuss said:

...I came across the idea of making patches with straight sides first when readings a copy of the Weisshaar book...i made a few of those and found it...time consuming to cleanly fit the corners of the patch...

I don't understand.  The Weisshaar-style patches have straight sides and rounded ends, but no corners.

[Jeffrey Holmes]

2 hours ago, Brad Dorsey said:

I don't understand.  The Weisshaar-style patches have straight sides and rounded ends, but no corners.

Yup... I assume he was talking about the transition from rounded to the straighter sides. I've personally not had difficulty with that.

[David Burgess]

4 hours ago, Andreas Preuss said:

Maybe a little late to join the conversation.

I came across the idea of making patches with straight sides first when readings a copy of the Weisshaar book. (I think it was back then in 1989) I neither could understand the reason doing so. 

However i made a few of those and found it a sort of time consuming to cleanly fit the corners of the patch.

My guess is that the straight sides were done to better match the appearance of the surrounding wood. I don't know of any downside to doing so, nor have I encountered any fitting challenges or "corners" when doing so.

[Mark Norfleet]

On 3/27/2020 at 7:02 PM, Jeffrey Holmes said:

That's pretty much the standard cleat shape I now use.  60 degree angle at the ends.  Jerry's shop uses something very similar...  I leave a little more in the center than you do, I believe. When things (cracks) get close, I also may alternate diamond shaped cleats (with the grain running off at about a 45).

 

I tend to alter the height and the non scooped part, as well as other dimensions, of the cleat to accommodate what I think is appropriate in a given situation.  You'll see that it is much broader on the ones I put in the old cello which had many cracks that had been aggressively cleaned at least a few times.  The cracks in the violin were new and probably caused by impact or compression on the bridge.  The poor thing spent 30 years in an unheated horse barn in SE Michigan and survived that with just a a few open seams until it's owner started using it again...

[Mark Norfleet]

On 3/27/2020 at 7:10 PM, Mark Norfleet said:

I usually leave more in the center too.

heres another shape I use.  I think the ends are all at 45 degrees.

For those new to this and pondering crack reinforcement methods, the situation in the far right of this photo is a perfect example of why cleats should not be too strong or aligned at their edges.  A new crack formed just to the outside of the old thick cleats that ended on the same grain line.  I either replaced or re-shaped them before closing the instrument.