Speed recomendation - Mortising Machines

[BOB OLINGER]

I'm about ready to write the check for a mortising machine. There are several manufacturers offering virtually the same machine for $250-300. One of the big differences is Shop Fox has a 3/4 HP and 3,450 RPM while the others have 1/2 HP and 1,750 RPM. The Shop Fox is about $50 more. That doesn't bother me that much, but I WOULD LIKE THE PROS AND CONS OF 3,450 vs 1,750 RPM'S. IS BIGGER BETTER FOR MORTISING???

[Frank Drew]

What type of machines are these, Bob -- hollow chisel mortisers; horizontal slot mortisers (unlikely at that price, I guess)?

[Kirk Poore]

I WOULD LIKE THE PROS AND CONS OF 3,450 vs 1,750 RPM'S. IS BIGGER BETTER FOR MORTISING???

My Greenlee has a 3500 rpm head. Faster spinning means a thinner chip for the same chisel insertion speed, so the chips should eject better. But from what little I've seen of them, the 1750 rpm machines do fine.

As for 3/4 hp vs 1/2 hp, I've never heard of anyone bogging down the motor on a hand-fed mortiser. I suppose it would be handy for chisels over 1/2", but then you've got to worry about whether the mortiser frame is beefy enough.

Kirk

[Terry Browne]

I have the Shop Fox and it does a good job for me. I don't experience burning on most woods even with the higher rpms. One real plus is that the Shop Fox has a long handle that gives good leverage when mortising. Some of the other machines have shorter handles and require a lot of force on the handle to cut a mortise.

[John Thompson]

I had a Shopfox for 5 years and yes it runs at 3450 rpm. I agree with what Kirk said but you have to be more careful with softwood running at the higher as I would occassionally get burn. You can plunge and retrieve plunge to eliminate it I found. But that speed and the extra power never bogged in any type wood even though I doubt a smaller motor combined with 1/2" and under bits would either.

My 600 + pound Industrial floor mortiser has provisions to run at both speeds even though I generally run at 1750 rpm even with hardwood. There might be an advantage with something as hard as black locust.. etc.. but I can't really make that call as I really don't know?

As for the shorter handles on other machines (the Shopfox has a very long one) just drop a longer metal pipe over the existing one to obtain the extra leverage.

Good luck...

Sarge..

[BOB OLINGER]

Frank,

Hollow chisel mortising.
Thanks,
Bob O.

[John Shuk]

Take a look in deals and discount forum. there is a scratch and dent Powermatic mortiser for about 250 from Redmond machinery.

[glenn bradley]

In a FWW review all machines were 1725 except one 3450. The author could tell no difference in the quality or speed of cut using good quality chisels.

[Wayne Cannon]

An article a number of years ago compared high- and low-speed machines and found the differences were not of the type that would affect selecting one versus the other.

The most significant factor to avoid over-heating (or jamming) was getting an appropriate gap between the bit and the chisel tip. I believe there was a suggested difference in gap for high- versus low-speed mortisers, but I don't remember.

The article was probably in American Woodworker or Fine Woodworking.

[BOB OLINGER]

Thanks for all the responses. My next project is some plantation shutters - quite a few. I plan to mortise and tenon the joints. I've not done many mortise and tenon joints. In reviewing posts of previous threads, you can get about as many recomendations as time to read them all. Several supported a router with a jig. I may reconsider that option, being I could use another good router with modern options. Does anyone care to comment on purchase of scratch and dent items such as the PM suggestion?

[John Hedges]

If you've got a lot of M&T joints get an FMT instead. You wont be sorry, but it does cost a bit more

[BOB OLINGER]

John,

Is an FMT a dedicated mortising machine.

[Wayne Cannon]

From Leigh Jigs' web site:
http://www.leighjigs.com/images/FMT%20pg%20D6.jpg

[John Hedges]

As far as fast and accurate, it doesn't come much better than an FMT.