Thread: DIY Furniture: Dowelmax or Festool Domino?

I'm done debating you, Silent. Please live up to your forum name.

There you go again. Can't you have a debate without getting personal? You haven't answered my question.

US-Oz, I'm not sure there is actually a greater surface area in a dowelled joint.

The surface area of a dowel is:

Pi * diameter * length

For a maximum sized dowel of 10mm, inserted to the typical half-length of 25mm, each insertion has a surface area of around 785 square millimetres. Thus, five dowels would have a combined surface area of 3,925 square millimetres.

If a tenon was cut to occupy the same outer dimensions, it would have a surface area of (2 * cheek area) + (2 * edge area). The maximum comparable size of the tenon would be approximately 80*10mm * 25mm depth, so the surface area would be 5,600 square millimetres.

In practice, it would be easy for the tenon to be made longer, which wouldn't be easy or practical with store-bought dowels. Thus a larger glue surface again.

I hope I got the maths right

Originally Posted by US-Oz

I apologize

I accept your apology.

Thus, five dowels would have a combined surface area of 3,925 square millimetres.

Most of which is end grain.

Originally Posted by US-Oz

I'm done debating you, Silent. Please live up to your forum name.

I know i get on peoples nerves, but thats harsh on Silent as he always puts across good points in a healthy debate. I havnt seen anything in this thread where he has put foward anything but good common sence facts. So the way i see it, you have started something you can not finish and are opting for the easy way out.

Originally Posted by silentC

Most of which is end grain.

Mother's milk to polyurethane glues.

Sigh.

OK, so provided you use at least three 'high quality compressed dowels', polyurethane glue, and the Dowelmax jig, you can get a joint that is stronger than a M&T, according to the jig manufacturer. Do I have that right?

So how long have you been using polyurethane glue in your furniture making?

Can't help yourself can you? Sorry, but barbs from someone like you are water off a duck's back.

I think Lignum is right, you've run out of steam.

Thanks guys, loved this thread, great entertainment and I've learned a lot from it. Hopefully I gave something back as well as took.

Originally Posted by US-Oz

No, the average HSS bit is not that high, mostly 50 and below.

Some are specially treated to make them harder and more brittle, especially Titanium, Cobalt & Black Oxide Drill Bits, and I suggest avoiding them for use in the Dowelmax.

Humm . . . I don't know where you're buying your HSS bits from but I just grabbed 3 HSS bits out of our workshop and went up to the Materials testing lab and measured the Rockwell C hardness.

Results:
Sutton standard HSS bit Rc 63.8
No Name Chinese brand HSS Rc 61.5
P&N HSS Rc 62.1

When I get a chance I will test a couple TiN coated bits.

The hardness testing machine is calibrated against a standard material obtained from the National Institute for Standards and Technology (NIST USA)

BobL, nothing like good, hard, facts ... can't argue with that

Sure you didn't drop them into some heat and cold on the way?? *Grin*

Bob, it hardly matters. The bushes do not wear out, ask Dowelmax. The side-by-side contact between drill bit and bushing would require very large differences in Rockwells to make a significant difference in a lifetime.

Originally Posted by US-Oz

Bob, it hardly matters. The bushes do not wear out, ask Dowelmax. The side-by-side contact between drill bit and bushing would require very large differences in Rockwells to make a significant difference in a lifetime.

I agree they probably do not wear out much, but I couldn't let a misconception about HSS being Rockwell 50 slide by without a comment. Rockwell 50 is an intermediate level hardness material as far as tools go. A simple check is to try and file a metal or woodworking tool with a standard file which are in the 63 - 67 Rc range. I cannot think of any HSS tool that I have been able to file.