Burning holes with down spiral bit

[aretstudent]

I am using a shelf pin jig and was told that it was best to use a router with a 1/4" down spiral bit. I did about six holes and started burning holes. I tried slowing down the router and speed at which I was plunging. Nothing seemed to correct the problem and I ended up burning the bit. Should I be using an up spiral bit or a drill bit? Any recommendations?

 

[GhostFist]

Don't quote me on it,but I think an up spiral bit would clear dust and thus reduce heat/burning.

 

[Tyler Ernsberger]

A up cut bit will prevent burning.  I just did 800 holes on one bit with no burning. 

 

[Acrobat]

Can someone tell me on what and where to use a upcut spiral vs a downcut spiral bit?
Is one for the router inverted in a table? or is say the downcut for going through material completely vs upcut just to certain depth?
Whats best for a bit that follows a template? i.e. like a MFS template.
I asked this question at a major specialist store here and the staff themselves were confused, and they had a router bit set sitting on their counter!

 

[Svar]

Downcut is to prevent chipout on the surface. However, its not good for holes, because chips can't escape.
There are bits with half upcut and half downcut spiral. They preserve both sides of the panel.

 

[rvieceli]

Here's a reasonable explanation:
http://www.newwoodworker.com/updowncutbits.html

Up cut clears chips better but the action can chip the top surface. Better for deeper excavations that will be covered by the tenon shoulder.

 

[Bob Wolfe]

for punching doles that are not through, use an upspiral bit that has a tip shaped like a fostner bit, the sharp outside spurs cut a clean hole on the surface and the chips are quickly removed.
The bit that came with my LR 32 has cut thousands of holes, still going strong.

BW

 

[Cheese]

for punching doles that are not through, use an upspiral bit that has a tip shaped like a fostner bit, the sharp outside spurs cut a clean hole on the surface and the chips are quickly removed.

This is the Festool version (491066) in 5mm.

 

[jmbfestool]

Downwards spiral bits are mainly for grooving or cutting holes larger than the diameter of the bit its self so to allow material to escape.
You can plunge directly down but not for to long because it will very quickly build up heat and waste material can not escape.  Downwards cutters are mainly for CNC's and require a 3D cut entrance into material to reduce heat build up.

Upwards cutter can be used manually and CNC. The cutters are designed for speed cutting and when working manually you are not moving that fast so its a little pointless.  Upwards cutter has a high risk of material tear out on the face.

A compression cutter (A hybrid upwards and downwards cutter) which Svar mentioned earlier.
These cutters are designed to cut materials in one depth pass. So that the upwards part of the cutter gives you a clean cut on the under side of the material and the downwards part of the cutter gives you a clean cut from above.  You can do multiple depth passes BUT you must go deep enough so that the downwards part of the cutter comes in contact with the material. If you dont its like using a short upwards cutter.  Again this can be used manually and CNC.  Its mainly used for just trimming manually and with a CNC its best cutter to use for cutting matrials in one pass.

 

[jmbfestool]

Left to right

Downwards cutter

Compression cutter (little hard to see sorry)

The rest are all dowel drills. Different sizes.

I dont own an upwards cutter not had the need for one.

To answer OP question its a dowel drill you require like the one Cheese posted and the ones I have.  These are designed not to drill right through the material although I do all the time no problem.  These give you a very clean tear free hole.

Dont buy Leitz im on my last Lietz bits they are a crap company and rip off-knock off.

[attachimg=1]

 

[jmbfestool]

Oh forgot to ask who the hell told you to use a downwards cutter? They need a slap!

 

[Cheese]

Just curious [member=5671]jmbfestool[/member], what don't you like about the Leitz cutters?

 

[jmbfestool]

Just curious [member=5671]jmbfestool[/member], what don't you like about the Leitz cutters?

A few things. 

I didnt like the Rep, had a memory like a gold fish.
Il advised me on what tooling. Bascislly their moto was sell the most expensive cutters.  The cutters didnt last long for the price I paid.  My cnc guy adviced me the correct cutters which are ALOT cheaper and last 10X longer. Wish I had asked him before.

Secondly I had bought other stuff for cnc for example collects.  I cant remember exact figures but I remember at the time i was able to buy 4 collects for the same price as 2 leitz collets.
  I had bought 2 leitz collects but ordered another 4 from my CNC guy. When they arrived I checked to see if there was any difference in quality between the Leitz and the 4 I bought.  They were IDENTICAL! The plastic box, the stickers, the colour. I even weighed them to see if same steel and they weighed Exactly the same.  The ONLY difference between them was Leitz had branded a very small logo on theirs.  I dont think a logo is worth £30-40  extra each.

Finally I bought a cutter block for my spindle moulder from Leitz and it aint that perfect like they claim.