New 12" Disc sander

60 or 80 grit

Russ

>The coarse grits remove the wood faster so there is less heat, and less heat means there is less burnishing of the end grain to interefere with a good glue bond.

Agree

Mark Kauder

>

A question for Russ

Keith Tompkins

>Russ, which joint would you think is stronger? A sawed joint or a sanded joint, assuming both fit properly?

Thank you Russ & Mark

Mango

>i'll take back the 100 & 150 blushing. It did come with an 80

Re: A question for Russ

Russ

>My simple answer is that the strength has more to do with the surfaces that were left behind than how they were made. The joint will be stronger when the end-grain of both surfaces of the wood is clean and open. The joint will be weaker when the surfaces are glazed, burnished, or otherwise sealed. It is easier for me to get that clean open end-grain with a sharp saw blade, than with a piece of sandpaper.

However, there are also some very expensive sawblades that I don't use because they leave a smooth burnished end-grain surface that is great for finishing, but not very good for gluing, (My opinion)

All other things being equal, the shear strength of the joint is important to the segmented assembly. Discounting the effects of creeping glue or starving the joint, the shear strength is what holds the joint together when there is differential movement between the adjacent segments. Good penetration into the wood of a good fitting joint will give the greater shear strength. Again, I am better able to get that penetration with a saw cut.

I could make the same joint by sanding with a coarse grit at a slow speed. That insures that the wood fibers are not layed over to close the surface, or gotten hot enough to burnish the wood and seal the grain with melted cellulose.

Like most things, others will have different experiences. Some of the best fitting and most durable joints I have seen in a segmented assembly were made by the late Ray Allen, and he sanded every joint. I am sure that Ray would have said that sanding was the better way to do it.

Could it be that the correct answer to your question is that, "It doesn't matter?"

Re: A question for Russ

Lyn J. Mangiameli

>A great answer, and with respect to the surface criteria, the best surfaces will be sliced by a flat blade such as a plane or mitre trimmer. Alas, probably not practical for most segmented forms because of their small size.