[joe123]

Hi,new to this forum. i just bought a grizzly g-0540 with plans on using it as a mortising machine. motor rpm= 3750 which i have heard some say this rpm is ok which i agree. but one question i have for this forum is if end mill bits are that much better? if a 4-flute bit will have issues getting the shavings out? or should i just use router bits? i did a quick test with a 1/4in router bit and was surprised how nice it works. this machine is very quiet which is also nice.
also i can't seem to find a vendor for longer than 2in tenons at a decent price. i bought it used for $140 so if this idea does not workout it not a big loss. thanks,joe

 

[Cherryville Chuck]

The more flutes, the less clearance for chips. Fewer flutes/teeth/etc should mean faster speed/ less power required. More flutes/teeth/ etc should mean slower speed, more power required but better finish.

I have some Amana boring bits that are 2 flute and carbide topped with outer scoring spurs. I would think you want something like that but they aren’t that long. Basically made for short dowels in Euro style knock-down type furniture. I’m not familiar with that machine but I think in most multiple boring machines every other bit has to be a left hand twist.

 

[joe123]

thanks for the reply, so at 3750rpm will a 4-flute have problems compared to a router bit?

 

[Job and Knock]

In Europe, where this type of slot mortiser originated, the norm is to use either a 1-flute or a 2-flute mortising bit with a lot of hip clearance. This is for speed and chip clearance. I tried end mills on variable speed routers many years ago and they don't work well in plunge routers at all. Go to a 4-flute end mill and the mortiser will almost certainly choke on the waste chips, be extremely slow cutting, be very hard work to use and probably suffer from scorching. Use the types of bit these were originally designed for and it will work far better

 

[aaronhooks]

I have an Italian slot mortiser and it runs at 1750 rpm. I have had a set of spiral up cut bits (1/4, 3/8, and 1/2) from Harbor Freight for years. I have cut a lot of mortises with them and they still work well. They are high speed steel.

 

[tacomamacxtech]

I found this response from another person:
(post #100689, reply #5 of 24)
by RickL in reply to woodman2263 [original] on Fri, 04/20/2007 - 16:14

I've talked with several folks over the past year who are using it successfully as a slot mortiser. Commercial slot mortisers run at 3,450 to 5,000 rpm. Use HSS two flute endmills for cutters. Another option is to buy the slot mortiser off the combo machines such as Robland, Minimax and build a base and add a router or my preference is a regular motor and run it at 5,000 rpm. They also come with a mortising chuck. Better than the Domino as you can use bigger tenons. A year ago you could have bought it for less. I've been using commercial slot mortisers for 25 years. It's about time folks figured out how good these machines are. Loose tenons are so much better. You can also do doweling and horizontal boring.

As far as the chuck and the bearings, it's not a big deal. Typically you are only taking light loads laterally as you nibble into the cut as you plunge in a bit at a time. You go side to side and slowly ease the bit in.

 

[joe123]

you guy's are right. today i borrowed a 4-flute end mil from my neighbor and compared the cut from my 2-flute router bit. the 4-flute cut was ruff looking with fibers hanging on. the 2-flute was nice. i think this machine will work out very nice for loose mortises.
when just typing this question on google and looking at responses i got answers back and forth. that's when i decided to post it here because if any forum should know it would be you guys. thanks

 

[joe123]

due to answers here and an experiment i did today i will go with standard 2-flute router bits. what brand and model is your italian made machine, i would like to look it up? that rpm is pretty slow but i guess it works. mine has a jacob chuck 5/8

 

[aaronhooks]

FBR model CM72 I might be remembering the motor rpm and not the speed at chuck.