WWA Info Exchange

I have a project with 80 1/2" x 5/8" through mortises in 1 3/4" oak. I have a delta drill press with mortising attachment. It's not been used much and I assume the chisel and drill bit are sharp. I get a lot of heat build up and smoking, enough that I'm worried about fire in the chips. This happens regardless of rpm used. With the short lever arm of the drill press (compared to a dedicated mortiser) it would seem like I can not go too fast. Why so much heat?

A couple years ago on this forum there was discussion about Harbor Freight's "cheap" mortising machine. It was all positive. It looks like the set up process is very similar and thus just as tedious. Is the only advantage the long arm to pull the chisel into the wood? Would it help me with this project in any other way? Does a dedicated mortiser make life any easier?

Thanks

Geoff

Sounds to me like the bit and chisel are not adjusted properly and the chips are not being cleared. Since I don't have one, I'll have to defer to someone who does to tell you how to adjust it properly. I've seen it somewhere, but don't remember where.

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John

The bit squeaks a lot, as if it's rubbing against the chisel. I have no idea how to insert it differently. Perhaps the depth of the bit makes a difference?

I haven't worked with a mortising tool before. It' such a hassle to set up I've done what little I've done by hand. But this time there's 80 to do. That's a lot of chopping.

Geoff

I'm sure it has something to do with the depth of the bit.

Here are a couple of posts that might help

http://www.woodworking.org/InfoExchange ... ortise+bit

http://www.woodworking.org/InfoExchange ... ortise+bit

I'm sure somebody will jump in here soon and give you the help you need. I just don't have any hands on experience with this.

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John

Your references to threads helped a lot. I guess I'm running it too fast and have the bit too low set. Regarding the mortising machine, it sounds like, as with everything in woodworking, how to do it is an individual preference.

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Geoff

I also had a Delta mortiseing attachment that would just burn and grab. I gave up on it and bought a Jet mortising machine and it works beautifully. After examining the Delta chisel I noticed it was ground on a different angle than the jet's. Since I had not retired then as a tool grinder I reground the Delta to the same angle as the jet (and extended the shank on the drill ) and now the Delta chisel works as well as the jet's. It was amazing what difference the angle on the chisel makes. Also a little bee's wax makes an excellant "lube " to prevent burning and grabbing.

That's interesting. What angle did you grind it at? Is there a conical stone commercially available at that angle?

I was just out to the shop and improved the over heating dramatically by lowering the drill bit a little as per the instructions in the thread, using the playing cards. I also slowed it from 3400 rpm to 1600.

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Geoff

Though this is for a dedicated mortiser, it is a great reference http://www.newwoodworker.com/setupmort.html

It sounds like the clearances on your chisels are not set right (see NB George's posting) it makes a big difference.

I have the HF mortising machine it works well it does take a little set-up. It does work better than any drill press mortising attachment.
I have done several hundred holes with mine and the bits are still sharp.

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"It is not a mistake it is a learning experience"
Monte

Geoff - You might like to have a layout gauge for that many mortises. Here is a gauge you could make.

HERE

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C J K
in beautiful -
Oxford GA, USA

All of this has been very helpful. Thanks everyone! But it also raises more questions.

Donald W, is there a difference in ease of set up between the Jet and the Delta drill press? Setting up is a pain with the drill press. Once I get it set up I fear taking it off to use the drill press for other things if I may still need same set up mortises before I'm done.

NB, your article is excellent. I still have a problem, though, with getting the chisel parallel to the fence. The fence on the delta table is very difficult to move. The slots are at an angle and there's no way to smoothly move or fine tune the fence's position. I tap/bang on the fence until the center of the fence is the distance from the chisel that I want then hold a steel ruler to the chisel and rotate the chisel until the ends of the ruler are the same distance from the fence. It's rarely right on first try and the process takes at least 15 minutes. Is there an easier way? Or will practice improve my skills to a reasonable time?

Daddy Gloves, do you know if there is a difference in set up ease between the HF machine and the more expensive ones? The pictures look very similar. I live 2 hours from the nearest store that has these machines so can not easily look at them.

Again, thanks to all for your help.

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Geoff

Use touch gages for setting. Finger squeeze, tighten fence, pull them out. Distance should be good.

Wouldn't be without these or similar. http://www.leevalley.com/US/wood/page.a ... ,240,41064

I am thinking the angle is a sixty degree included angle. (The old mind is just that, an old mind ). I find the Jet is much easier to set up and use now!. I modified mine by adding a riser block and a cross slide vice. I never liked the holdowns or fences on any of the mortising attachments or bench top machines. I have noticed that some of the manufactors are now putting cross slide vices on their machines. While I made mine riser blocks are available for many of the commerical bench top machines.I'll try and get over to the shop and get a picture to post for you tomorrow.

I had to add a 1/2" spacer on the fence for the bit to clear the hold down.
Squaring the bit to the fence is similar to others.
There are 15% off coupons in several magazines Car and Driver for sure.

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"It is not a mistake it is a learning experience"
Monte

Here is a photo of my mortiser with the reiser block, and cross slide vice. I also added some "outriger clamps " when I put on the vice. But I have found they are not needed.

See "mortising machine with vice"

Sorry about the tilt. I thought I had the picture rotated.

here is another try

See "mortising machine with vice"

I find the cross slide vice lets me locate my mortises easily and gives me three inches of travel without reclamping. And if I do reclamp location is steady.

This is all helpful. I have a meeting in St. Paul tomorrow, just 4 blocks from Seven Corners Hardware. They have Jet, Delta, and Powermatic. If they have the mortisers in stock I can see first hand what we're talking about. There's also a harbor freight just south of St. Paul on my way home. If they have one in stock I can stop there as well.

Geoff

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Geoff

I went to 7 Corners yesterday and looked at a Jet, Delta, ShopFox, and Powermatic side by side. There was a clear difference between the less expensive (ShopFox) and the others in ease of use and apparent precision. Whether it will make a difference to me when I start using it is another question, but I got the Delta.

Thanks much to all for your help.

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Geoff

Sounds like you tried to sneak in a gloat in your most recent post So, you decided to go with a dedicated mortising machine?

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John