Drilling blanks

[frankonthetis]

Drill all my blanks using my lathe. One constant issue is when using the 8mm [.3150"] Norseman bit the hole is too tight for the tube to slide through. Have to reverse the blank and re-drill which then allows the tube to fit. This only happens with the 8mm bit, all the other Norseman bits give the proper hole size for the tubes to slide in. This happens on every type of 8mm kit I use, so the question is do others have the same issue with their 8mm bits?
Realize when wood is wettish any drilled hole will be tight on the tube as the heat created by the bit will shrink the hole.
Is this only an issue with the Norseman bits? They are supposedly a good product and that is true except for the 8mm bit.

 

[Curly]

Get a letter O bit and run it through the Norseman hole or just drill with the O bit. It is .001" bigger than the 8mm bit. I that doesn't work look for an 8.1 or 8.2 mm bit at one of the machining tool suppliers in Vancouver. KBC for example.

Pete

 

[frankonthetis]

Thanks Pete, think there might be a O bit that was for one of the LV kits.

 

[Gordon]

I have kits that take 8mm tube and I had the issue with tubes not fitting in after drilling out. I bought 8.1mm drills and that cured the issue, I use gorilla glue which also takes up any potential slack from using the slightly oversize drill bits.

 

[alpha1]

I drill 8mm tubes all the time with no issues. I just use normal HSS drills.

 

[frankonthetis]

Thanks Gordon & Dave. Have the 0 bit Pete mentioned and will give that a try. It was just annoying that the 8mm holes were such an issue.

 

[21William]

My local discount store used the sell loads of metric drill bits off cheap. Most of them were not whole millimetre sizes. I bought loads of them with sizes like 5.2mm 8.8mm and 8.9mm etc. you never know when they’ll come in handy. I also make sure to replace any blunt or broken bits from my Imperial set.

 

[frankonthetis]

Update on Peter's suggestion to use a 0 bit after using the 8mm bit. Had occasion to use the 0 bit after pre-drilling with the 8mm bit and it worked a charm. Tube slid in effortlessly. Thanks again Peter for your suggestion.