Slot drills in a woodworking router?

[Robin GrahamParticipant @robingraham42208]

I have a one-off woodworking project which needs slots cut in sapele. I haven't got the right size router bits, but I have got a fairly comprehensive collection of HSS slot drills. I also have an ER20 collet chuck for my router, but only a half inch collet at the moment. I can buy a set of ER20 collets for less than the price of a couple of decent router bits – that would allow me to use any of my metalworking bits in the router, so may also be useful for yet unthought of projects.

Are there reasons why this wouldn't be a good idea? Different cutter geometries perhaps?

Robin.

[Robin GrahamParticipant @robingraham42208]

[Grindstone CowboyParticipant @grindstonecowboy]

The spiral flutes will probably tear up the grain along the edges. This may or may not be acceptable to you for what you are doing.

[Paul LousickParticipant @paullousick59116]

I have used a slot drill in my mill to machine hardwood timber. (Not sure about softwood) They have to be very sharp or they will burn the timber even though they are OK on metal. Would be even worse at the speed of a router.

Paul.

[John BaronParticipant @johnbaron31275]

Hi Robin, Guys,

I agree with the above comments !

It works well the other way round ! I've often used carbide router tool bits on the mill for cutting steel, unfortunately slot drills don't work in wood… though you might like the smoky smell

[JasonBModerator @jasonb]

Ideally you want a solid carbide slot drill with a high helix angle such as those for aluminium which will mimic a up-cut spiral router bit though it still won't cut as well. I'm assuming you don't have one of those either so an HSS one won't last long in sapele.

Having said that I have used 3-flute HSS bits to cut finger joints without problems in the mill.

Edited By JasonB on 11/08/2019 07:18:15

[egaParticipant @ega]

JasonB:

I looked at your finger joint link and see that you are using the excellent BMK cramps. I have tried without success to source these from time to time and wonder where you got yours.

[JasonBModerator @jasonb]

I wish I could get more, Must of had those for about 20yrs bought from Woodcut Trading Co and about £5 each if I remember right.

Though some say I have enough clamps already!

[egaParticipant @ega]

JasonB:

Thanks – although it looks as though they "went bust" some time ago.

I think my own modest set of BMKs was bought about the same time ago; rather like spindle hole size one never has enough!

[Robin GrahamParticipant @robingraham42208]

Thanks, Sounds like it isn't a good idea. I'll stump up for proper upcut router bits or rethink.

JasonB – your link to finger joint cutting was very interesting. My project is to make a small finger jointed box but with shelves so 'slots' (dados?) to accommodate. I had thought about cutting the fingers on the mill, but I don't have the headroom if I hold the work in a vice. It looks like you held the work directly to the mill table, but I can't figure out how from the pics.

I've spent today making a cross cut sled for my table saw with the intention of making a finger joint jig, but it would be much simpler to do it all on the mill if possible. Sled will surely come in handy for other things though!

Robin.

[John ReeseParticipant @johnreese12848]

The slot drills designed for aluminum would be my choice.

[JasonBModerator @jasonb]

Robin there is an angle plate behind the wood and the two G-clamps are holding it to the angleplate. For the small loads you could prabably make a tall angle plate from two bits of MDF and add trangular fillets for stiffness

The table saw method does work though ideally you want a flat top blade where the teeth are ground straight across rather than the usual alternate bevel, these are often sold as rip blades but not all are flat. The sled method can also be used with a router mounted in a table

[Robin GrahamParticipant @robingraham42208]

Thanks Jason, all is now clear – I have dug out an angle plate which should work.

Point taken about ATB blades. The guy on the jig-making video I've been looking at swipes the work sideways between the stops a couple of times presumably to cope with this, although he doesn't go into the problem.

Robin.

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