What slot mortising bits do you use? Sources?

[Tom Hyde]

I have a Felder FD250 horizontal slot mortiser.

I've been using Klein (Italy) birdsmouth slot mortising bits purchased through Laguna but I'm not sure they will continue to offer them. Not on their website anymore. Just had to go through some hoops to order a set.

The bits sold by Laguna are Imperial-sized birdsmouth bits from Klein (Italy) tools sold in a set of five (1/4" - 3/4"). About $330. Sharpening does not affect size. These are pretty nice with a 4" cutting length. All work well, except the 1/4" which is too small and whips too much.

I've looked at the Felder bits but they are only two flute as opposed to four flutes on the Kleins. And I've not heard good things about the Felder bits. But again, haven't tried them.

I assume MiniMax/SCM sells slot mortising bits?

What do you use, source?

(BTW, endmills don't work well in this application, and I don't have rpm control on my machine)

[Brian Holcombe]

I have a set from Leitz that work well.

[Jeff Duncan]

I have a Felder FD250 horizontal slot mortiser.

(BTW, endmills don't work well in this application, and I don't have rpm control on my machine)

Just out of curiosity..... why don't the end mills work? I've been using them for years, mostly 4 flute roughing mills, less than $50 a piece for the better ones from MSC. Cut though oak like butter and last a good long time. Some of the smoother finish ones don't work great.... won't drill into the end grain parts well. Had to try a bunch to find ones that did what I needed.

good luck,
JeffD

[David Kumm]

Rangate sells a carbide set. Clico used to make a single flute but most now are double. I never liked a spiral on a hand mortiser as I felt the bit was pulling into the cut and larger diameter bits could beat me to death. I do use them on my Bacci and they leave a clean cut. Dave

[Rick Potter]

I have an unused set from Laguna I might be willing to part with. If interested PM me.

[Tom Hyde]

I have a set from Leitz that work well.

Excellent, thank you! Turns out they have a shop nearby, and could be my go to place for sharpening as well.

[Tom Hyde]

Just out of curiosity..... why don't the end mills work? I've been using them for years, mostly 4 flute roughing mills, less than $50 a piece for the better ones from MSC. Cut though oak like butter and last a good long time. Some of the smoother finish ones don't work great.... won't drill into the end grain parts well. Had to try a bunch to find ones that did what I needed.

good luck,
JeffD

Hmm. Well I use a lot of 3/4" and my understanding is these will pull into the cut which is not what you want with the hand-controlled mortiser. I see MSC has more than 4,000 roughing mill choices. Which ones work for you?

[Tom Hyde]

Rangate sells a carbide set. Clico used to make a single flute but most now are double. I never liked a spiral on a hand mortiser as I felt the bit was pulling into the cut and larger diameter bits could beat me to death. I do use them on my Bacci and they leave a clean cut. Dave

Yeah the Rangates look really nice but unfortunately are too short. I need a 100mm (4 in.) cutting length for cutting through-mortises in door and cedar gate stiles, and full 4" for mortise in rails (for sllip tenon).

[Kevin Jenness]

" why don't the end mills work?"

As Dave points out, the spiral upcut end mills tend to self-feed. On my Steton mortiser with dovetail ways this is not generally a problem (although I did have a 4" d.o.c. 5/8" diameter end mill that almost worked its way out of the chuck). I found when using a Felder with the low friction linear bearings that spiral end mills over 3/8" diameter were pretty much like riding a bronco, so we used bird's mouth bits. They won't bore straight in so you have to ramp the feed. They are easily sharpened with no diameter change.We got some from MiniMax, they may still supply them. Here is a source for bits up to 1/2" diameter https://www.icscuttingtools.com/new-products/mortise-bits.htm.

As a general rule, use the shortest, stoutest bit available for the job to avoid tapered mortises from bit whip.

[Brian Holcombe]

It's not just the bearings on the Felder that are the issue, it's the light motor mount and joystick feed. When the mount flexes it sends the bit into a climb cut and rams the motor into the end stop.

Fixing the motor mount (making a seriously heavy replacement) and changing the feed to a rack and pinion allowed it so I can use upcut spirals in the machine. Before that it was impossible.

[Patrick Walsh]

Brian dies the Felder mshunevwork to your standard now after what you did.

Kinda figured not with the maka finding its way home.

It's not just the bearings on the Felder that are the issue, it's the light motor mount and joystick feed. When the mount flexes it sends the bit into a climb cut and rams the motor into the end stop.

Fixing the motor mount (making a seriously heavy replacement) and changing the feed to a rack and pinion allowed it so I can use upcut spirals in the machine. Before that it was impossible.

[Brian Holcombe]

Brian dies the Felder mshunevwork to your standard now after what you did.

Kinda figured not with the maka finding its way home.

Yes, very much so. I can mortise (square chisel) right to the line in harder woods like ash without noticeable deflection. I can bore any size hole without issue and I can cut rapidly using router bits without banging the stops or having unexpected depth changes.

Square chisel mortising strains the machine most, so I will show the results of that. These are untouched up afterward by hand, so just right off of the machine showing what it can do. I set stops so that it cuts right on the line. My goal was to do zero cleanup afterward.

[Brian Holcombe]

I have an additional support to the fence planned along with air clamps, probably 1st quarter next year after the Maka is complete. So there is still some tuning to be done, but the machine is working nicely. I'm happy to keep it at this point, I was considering letting it go for a while.

Also, it is now silent, the stiffer mount killed off all the noise that the flexable mount was making.

[Brian Holcombe]

Down cut spiral, shallow mortises;

[Mike Tagge]

If Rangate is too short, give Greg a call. I was looking into longer bits a while ago before I had a part machined that brought the table into a workable distance. Greg seemed to be able to get longer ones.