I want to dowel hardwood parts together using 3/8" commercial dowel stock that you buy at places like Woodcraft.
I used a digital caliper to measure the diameter of the 3/8" doweling, and it appears to run about.375", although it drops below that frequently and goes above that less frequently.
I suspect there are multiple factors that "could" affect the actual size of drill bit I need;
- the actual (not "nominal") diameter of the bit (the 3/8" carbide Forstner bit I measured today had an actual diameter of .377")
- the combined runout of the drill spindle, drill chuck, and drill (which I don't know how to measure properly)
I tried a quick little experiment today:
- I used first a carbide Forstner 3/8" bit and then a 1/2" spade steel bit
- I drilled first a 3/8" hole and then a 1/2" hole into a block of 3/4 plywood. I had the plywood firmly clamped when drilling each of the holes
- I measured the diameter of each drilled hole in the plywood using a digital caliper, and found that the hole was, in each case somewhere in the .007" to .010" range larger than the corresponding bit
I have a 1-ton arbor press to seat the dowels with an interference fit.
So, if I want a good interference fit for that 3/8" doweling:
1.Does the drill runout affect what size of drill bit I should use, or does the bit hold its hole diameter once it starts into the wood?
2. what size of (carbide Forstner) bit should I use?
3. Do all 3/8" bits have the same actual (not nominal) diameter, or do they vary?
Jim G
I used a digital caliper to measure the diameter of the 3/8" doweling, and it appears to run about.375", although it drops below that frequently and goes above that less frequently.
I suspect there are multiple factors that "could" affect the actual size of drill bit I need;
- the actual (not "nominal") diameter of the bit (the 3/8" carbide Forstner bit I measured today had an actual diameter of .377")
- the combined runout of the drill spindle, drill chuck, and drill (which I don't know how to measure properly)
I tried a quick little experiment today:
- I used first a carbide Forstner 3/8" bit and then a 1/2" spade steel bit
- I drilled first a 3/8" hole and then a 1/2" hole into a block of 3/4 plywood. I had the plywood firmly clamped when drilling each of the holes
- I measured the diameter of each drilled hole in the plywood using a digital caliper, and found that the hole was, in each case somewhere in the .007" to .010" range larger than the corresponding bit
I have a 1-ton arbor press to seat the dowels with an interference fit.
So, if I want a good interference fit for that 3/8" doweling:
1.Does the drill runout affect what size of drill bit I should use, or does the bit hold its hole diameter once it starts into the wood?
2. what size of (carbide Forstner) bit should I use?
3. Do all 3/8" bits have the same actual (not nominal) diameter, or do they vary?
Jim G