Help - Slot Mortising Bits Slipping in Wescott Chuck

[John TenEyck]

I bought 1/2" and 3/4" Amana slot mortising bits (see link below) for my Mini Max FS35 J/P mortiser, which has a Wescott chuck. I've never used it before. I chucked in the 3/4" bit like I would a router bit, not quite bottoming it in the chuck, and tightened it as tight as I could with the 4 or 5" Allen wrench. I made two mortises about 2 inches deep by 3 inches long without problems, taking 1/16 - 1/8" passes. They looked pretty good. So then I tried another mortising by plunging full depth on each end first. Uh Oh. I got about 1/2" deep on the first hole and then the bit slipped in the chuck. Crap. I stopped the machine and checked the bit. It's now slightly scored on the shank.

So what am I doing wrong here? Is a Wescott chuck not even designed for round shank bits? Any help would be appreciated. Thanks in advance.

John

http://www.toolstoday.com/p-5886-up-shear-bit-slot-mortiser-router-bit.aspx?&variantids=9783,0&keywords=45540

[Rod Sheridan]

John, whenever I've used a slot mortise I go in a few mm, sweep side to side, go in a few mm, repeat.

I've never tried to do a deep cut in any other way.........Rod.

[John TenEyck]

Yeah, that's how I did the first two. Have you ever had any problems with the bits slipping in the chuck? The chuck just doesn't seem to grip the bit all that securely. The jaws on the chuck have flat surfaces. The bit is round. Just doesn't sound like a good combination yet all the slot mortising bits I see (on-line) are round.

John

[Jeff Duncan]

My experience has been the same as Rod's and never had any problems with slipping. Trying to do a full depth run with a 3/4" bit is a substantial bite to say the least. My chuck only goes to 5/8" and even then I do the shallow passes.

good luck,
JeffD

[Peter Quinn]

I've had one get loose when I was pushing too hard. Yours may have been sitting for a whilem? Try opening it all the way up, blowing it out and cleaning any surface rust/oxidization from the contact surfaces, clean the shank of a new bit with some naphtha or alcohol, they are usually oiled a bit. A little fine rust makes a great dry lubricant on metal...so lose that. Other wise, the tighten it hard and don't take a full depth pass. Some bits can plunge that deep on he ends, others can't, I don't know you're well enough for know which it is.

[John TenEyck]

That was a good idea Peter but it didn't help. I cleaned both the chuck and bit, chucked it back in and tightened it as hard as I could. I set up for a new cut; the test piece is black walnut BTW, so not something nasty. I took very small cuts, no more than 1/16", by plunging at one end and then moving the carriage slowly to the other end. Plunge another 1/16", or less, and traverse back. And then I saw it happen. The bit grabbed for no apparent reason and pulled forward into the wood - and out of the chuck! Not all the way out, but it must have slipped at least 1/8" and probably more. I stopped, of course, and took the bit out and saw some spiral scratches on the 1/2" dia. shank (for Jeff's benefit; the bit is 3/4" but the shank is only 1/2"). This ain't good.

I looked at Amana's website again and it said these bits are for "fast cuts and chip clearance". The bits are an upshear design which explains why they want to pull into the wood. I can see them working very well if the chuck can hold the shank securely but it's clear the chuck on my machine can't. I think these are not safe in my machine and I need to go with birds mouth bits. Anyone want to buy one of these that's only cut about 5 mortises?

http://www.amanatool.com/products/router-bits/straight-plunge-router-bits/mortising-router-bits/45544-carbide-tipped-up-shear-bit-slot-mortiser-3-4-dia-x-1-inch-x-1-2-shank.html

(http://www.amanatool.com/products/router-bits/straight-plunge-router-bits/mortising-router-bits/45544-carbide-tipped-up-shear-bit-slot-mortiser-3-4-dia-x-1-inch-x-1-2-shank.html)I also have a 1/2" diameter one that hasn't even been out of the box.

John

[mreza Salav]

I find spiral bits are sometimes wild/difficult to predict. Seems you also forgot the comment I gave earlier "Whatever bit you get don't go plunge more than a little" :-) I once broke a 1/2" spiral bit in a router by plunging a little too much and scared the @#$@ out of me.

I don't have experience with that chuck or bit. If your chuck is indeed square and your bit shank is round I don't think they are meant to be used with each other, there is too little contact area to hold the bit in place.

[John TenEyck]

Mreza, this is a picture of the Wescott chuck on my machine. When I look at the literature for new MM machines it states they too have a Wescott chuck, so I assume yours does too, no? https://iwoodlike.com/product/accessories/combination-accessories/westcott-chuck-0-16mm (https://iwoodlike.com/product/accessories/combination-accessories/westcott-chuck-0-16mm)Does this look like what's on yours? Same question to others.

I inspected the chuck again this morning and can find nothing wrong with it. But the square jaws sure suggest it should be used with square shank bits, yet I've never seen such an animal. I know nothing about slot mortisers, however, so I'm completely ignorant about the chucks, bits, etc. Any help is appreciated.

John

[Peter Quinn]

I don't think it's an issue of square shank, no drill press has round jaws, they all have flat faces. Wescot is a four jaw chuck versus three on a regular drill press. Only a collet such as on a bridge port of router matches the shank diameter. I have this odd way of just snugging up the chuck, backing off a hair to make sure the drill is centered, then snugging it up real hard, seems to work better for me. It's my understanding that the advantage of a wescot chuck over a typical Jacobs 3jaw chuck is that it's self centering, but IME not perfectly so.

[Kevin Jenness]

Westcott chucks like yours are standard equipment on the manual slot mortisers I am familiar with (Steton Felder, Bini, Griggio) and are used with round shank bits. I have found that they can slip with large diameter and/or long spiral bits, especially if used aggressively, so I stick with the shortest bit of a given diameter that will do the job and take light depth cuts when sweeping side to side. I have used a 5/8" Amana bit like the one you are using, but cut the shank shorter after initially experiencing rough cutting and whipping of the bit, after which it cut ok but not as smoothly as a typical end mill. I have a 3 1/2" cut length 5/8" diam. endmill that slipped in my chuck cutting cherry no matter how careful I was; I sidelined it in favor of a 2 1/2" cut length bit, problem solved. Birdsmouth style bits have less of a tendency to work themselves out of the chuck than spiral bits, but excessive length still results in vibration and inconsistent mortise sizes. My experience is that mortises deeper than 4 times the bit diameter are likely to be problematic with that type of machine. I do know of one shop that had a set of tapered collets made for their oscillating mortiser, but that is a rather expensive solution. If there is a more appropriate/affordable chuck out there I am not aware of it.

[Robert LaPlaca]

John, I have a mortising table on my MM J/P.. I use the birds mouth bits and as Rod stated taking only take small amount of material in each pass.

One thing for sure, is the birds mouth bits would never be described as self feeding, if anything one needs to eat their Wheaties to get the bits to take a deep enough cut. I think the Westcott chuck was not designed for the self feeding nature of the Amana bits, kind of makes me wonder what machine the Amana bits were designed for though..

[mreza Salav]

I don't have that chuck John (was about to add the mortising attachment but didn't). Others who are more experienced with that setup have given you comments.
My experience with spiral bits is they can be very aggressive if biting too much into the wood, and they have tendency to move in the collet/chuck due to the nature of their operation, this can be sometimes very dangerous if they are not very secure in the chuck/collet.
Out of curiosity do the jaws of the chuck have completely flat surface or a curvature (like a lathe chuck) to have a two-point contact on each jaw (instead of one)?

[John TenEyck]

Thanks everyone for your replies. I think the root of my problems are most likely related to the size of the bit. A 3/4" cutter with a 1/2" shank puts a lot of torque on the chuck/shank surfaces. Add in a little vibration from the long shank and aggressive cutting behavior of the Amana bit, and it's pretty easy to understand how it slips. Sort of like a 1/2" drill bit with a 1/4" shank in a standard drill chuck. In any case, I don't think this bit is safe to use with the chuck I have.

I'm going to order a birds mouth bit and see how that works. Stay tuned.

John

[John TenEyck]

Mreza, the chuck has opposing V-shaped jaws. Each jaw is formed of multiple, alternating pieces steel set an angle to form a V, and each of which provides a point of contact to the bit shank. There are maybe 10 or 12 sections to each jaw, so you end up with a lot of points of contact but still not much contact area. The acme threaded rod that pulls the jaws together has a rather coarse thread, too, and I wonder how much force you actually can apply to the jaws. I'm sure it all works well enough with small diameter bits, but when you get up to these larger ones it looks challenged.

John

[Peter Quinn]

You are pushing the upper limits of that whole mechanism with a bit that diameter. Probably would be easier to use a similar bit of smaller diameter, probably wouldn't go in as deep, but do double tenons of a smaller diameter rather than one big bite. I've used that strategy effectively with mine. I've done 3/4" mortises on a Bridgeport, using a 4flute end mill, but that's a 3/4" shank, M5 collet of matching diameter and a 2500 pound machine with brutally solid hold downs and table so there is no slapping or deflection. My guess is you could get the big bit to work, but you need real good workpiece support to insure no deflection of workpieces and very light sweeping passes, particularly as you approach full depth.

[Jeff Duncan]

You may also want to try out a self-centering roughing mill. That's what I use on my Bini and find them to do a very nice job at less cost than specialty bits. I haven't tried anything larger than my chuck can fit which I believe is 5/8". These bits don't "pull" into the wood and cut pretty fast. I use mostly maple and white oak and they cut a LOT of mortises before needing replacing.

The passage door style I make the most of I use 2 3/8" tenons per rail. Using 2 smaller tenons in 1-3/4" stiles and rails gives more gluing area than 1 larger tenon. It's worked very well for me anyway.

good luck,
JeffD

[Joe Calhoon]

Westcott chucks like yours are standard equipment on the manual slot mortisers I am familiar with (Steton Felder, Bini, Griggio) and are used with round shank bits. I have found that they can slip with large diameter and/or long spiral bits, especially if used aggressively, so I stick with the shortest bit of a given diameter that will do the job and take light depth cuts when sweeping side to side. I have used a 5/8" Amana bit like the one you are using, but cut the shank shorter after initially experiencing rough cutting and whipping of the bit, after which it cut ok but not as smoothly as a typical end mill. I have a 3 1/2" cut length 5/8" diam. endmill that slipped in my chuck cutting cherry no matter how careful I was; I sidelined it in favor of a 2 1/2" cut length bit, problem solved. Birdsmouth style bits have less of a tendency to work themselves out of the chuck than spiral bits, but excessive length still results in vibration and inconsistent mortise sizes. My experience is that mortises deeper than 4 times the bit diameter are likely to be problematic with that type of machine. I do know of one shop that had a set of tapered collets made for their oscillating mortiser, but that is a rather expensive solution. If there is a more appropriate/affordable chuck out there I am not aware of it.

All of the above has been my experience also Kevin.
We used to do a lot of slot mortising on A SCM combo machine and later on a Kolle mortiser. We found the end mills on the left side in the picture worked better than the birds mouth or the other type bit used in these. We did try the long bits shown for lock mortises but you have to go in real easy and still not good results. Our current machine is a Hoffmann with a collet chuck. It works good for drilling but not so good for mortising as the collets do not take side pressure as well as the Wescott type. We have tried a 3 jaw Jakobs chuck but that does not work very well for mortises. I think the Wescott is the best for this app and not expect too much.

.325660

[John TenEyck]

Thanks for that info. Joe. I think after reading your and others' experiences that I'm going to buy a couple of cheap 2 flute end mills in the 3.5" length range, which will give me a max depth of only around 1-3/4" but that's still enough for the project I need it for. I bought the long Amana bits thinking I'd be able to use them for large, deep exterior door mortises and that's still a goal. If I can't get it to do that then it's fairly useless to me. For smaller, shallower mortises my shop built horizontal router mortiser is faster and easier to use and makes beautifully smooth, straight mortises. Actually, it can easily make 2" deep, 1/2" wide mortises. It's disappointing to see that what appears to be a beast of a mortising machine in the Mini Max has such a weak link in the chuck. If a Wescott chuck is the best there is on these machines that doesn't speak too well for their utility in my mind. But I haven't given up complete hope. It seems to me that the shank of the bit could be ground square and the corners chamfered so that the chuck could grip it securely, or a piece of square stock could be bored for the 1/2" shank and brazed or welded to it. I'll have to talk with a local machinist to discuss those ideas.

Thanks again, everyone. More comments always appreciated.

John

[Warren Lake]

I have a slot mortiser on an SCM Combo and have never had any bit issues with it. Do you have to use that chuck system? Mine just has a threaded nut type thing and there is a collet that goes inside. Its very much like a router system with the end nut and collet inside the shaft bore. Im not sure what the maximum length birdsmouth type bit is that i have and ive never tried extra long end mills in it. I find a chisel mortiser easier to use and faster and you can get more depth depending on the chisel supplier something I have to research again.

I dont think there is any pulling force on a birdsmouth cutter compared to some of the others but that really should not be an issue, if a router can hold those bits then the mortiser chuck should be able to do it as well.

can you not switch out to this old style system for holding your bits? its simple and from using it in the past had no issues.

[Joe Calhoon]

Hi Warren,
Can you take a picture of that chuck? I think my SCM combo was the same as yours but it had the Wescott type.

John,
don't give up on it we cut a lot of mortises on these. It takes a little feel and practice. True, there are better machines for this but they do work with the right bits. Our SCM had a fixed bit coming off the planer head with a moving cast table on dovetail ways. You could really go at it hard on this machine because the table took a little effort to move. When we went to the Kolle it had a moving head on ball bearings and it took a little getting used to so as not to overfeed. One thing you can do is make a deck of 1/8" or so shims, fix them behind the depth stop and remove one with each pass. This will give you a feel for not overfeeding. If the machine had easy moving table or head it is easy to take too much without realizing it.
I think it would be worth trying the bit Jeff recommended.

[Warren Lake]

Hi Joe

yes I can but cant get to it till tonight then just have to figure out how to post as havent done that before. Will shoot the nut and insert collets and shaft end. I like the side to side motion on the slot mortiser but the Invincible is a bit of a primitive beast probably 50 years old. Its harder for me to see my stop lines on horizontal than vertical. Once ive done a few accurate stops then it sort of acts as a wall to stop the bit, almost by sound. I think newer horizontal machines have an adjustable stop system and there was also one on the Chisel mortiser that I didnt understand so its off for now but its so easy to see the lines on that machine its not needed.

and I can envision a nicely sliding table would be different like driving a 60's car without power steering then going to power steering. As a kid my father only had cars with manual steering. My grandfather was an engineer at GM and his car was a 65 Pontiac custom sport. I went out with my father first time he drove it and he glanced a curb as the steering moved so easily compared to all his own cars. I try to keep the dovetails clean still there is some drag in the SCM on the side to side motion. Good idea on the stops Joe will have to try that.

[John TenEyck]

Hi Warren. The Wescott chuck on mine threads onto the end of the planer head - I think. So it theoretically could be changed out to something else. How much money I want to throw at it is another issue, however. It's hard to believe I'm the only person who has tried using a 3/4" bit in their Wescott chuck, Mini Max mortiser. I want to sort out whether the bit is the root of the problem or the chuck before even considering changing the chuck.

Either people misunderstood what I said or I didn't say it well enough. Yes, I did try a plunge cut and the bit slipped. But the more important issue is that the bit slipped, several times, when taking well less than 1/16" cuts and moving the carriage slowly. And in one case, not only did the bit slip cut it started to walk out of the chuck. This is a complete show stopper IMO. And when that happened the bit was less than 1/2" into a cut so it's not like I was buried 3 or 4 inches deep. The bit only has a 1" cutting length anyway, so even deep cuts shouldn't be a problem.

You know how some drill bits have hex shanks on them? They don't slip. It just seems like someone would make square shafted bits for use in Wescott chucks.

Anyway, I am going to try a shorter 2 flute end mill as Jeff recommended and see how that goes. Still gonna be 3/4" diameter though. Otherwise, I might as well use my horizontal router mortiser.

John

[John TenEyck]

Just a further note. I realized I had a brand new 1/2" diam. x 1/2" shank Onsrud upcut spiral router bit, so I chucked that in the mortiser and had no trouble cutting a very smooth mortise about 1-1/4" deep. I took no more than 1/8" per pass; sure takes some effort to plunge forward each time compared to the Amana bit however. But no chattering and the mortise was exactly 1/2" wide and straight sided. And no slipping of the bit in the chuck.

So I think this speaks well of using 2 flute center cutting end mills.

John

[Kevin Jenness]

John. I have used a short (1 1/4" cut length, 1/2" shank) Onsrud end mill in my Westcott chuck equipped mortiser with good results, as well as a longer (2" cut length, 1/2" shank) birdsmouth bit (from MiniMax, made by Onsrud) in another machine. I think the trouble you were having is due to the excessive length of the Amana bit you were using. As mentioned previously, I got acceptable results after shortening the Amana bit I was using (although the fact that the shortened shank was not ground where the chuck held it probably increased runout). Any deflection is magnified by the large overhang, and the upcut spiral edge tends to pull the bit out of the chuck. All the problems I have had have been with long bits. These machines and their tooling are just not made for really deep mortises - hollow or oscillating chisel machines are a better choice. However, the 2-2 1/2" deep mortises they are capable of are quite adequate in my experience to hold together full size doors, and are a good joinery option for use with stub tenon/cope and stick cutter sets for shops that lack the machinery and tooling to do traditional coped tenons.

[John TenEyck]

Thanks for that info. Kevin. I've thought that one option for the Amana bit is to have the shaft turned true, just above the shank, and then cut the shank off. That would increase the shank diameter to 5/8" and shorten the bit. Together, it should run true, have a lot less tendency to vibrate in the cut, and the larger shank should hold better in the chuck. That should get me to at least 2-1/2". In the meantime, I'm going to order some 2 flute spiral end mills so I can mill at least 1-1/2" deep.

John

[Jeff Duncan]

If you want to retain some of the speed of cut you actually want a 3 or even 4 flute roughing mill. The cut won't be as pretty as a normal end mill, but it's a mortise….it doesn't need to be. Also make sure it's center cutting, I forgot this little detail on a bit I ordered and there was no plunging going on at all! I order mine from MSC and usually go with the cheaper import ones. I figure if it's good enough for steel than it'll be just fine in wood, so why spend more on the more expensive versions? You might want to get one or two smaller mills and see if they work out any better for you before spending on the larger ones? They're pretty affordable compared to the specialty bits.

good luck,
JeffD

[Warren Lake]

325695

so whats the trick to getting this photo to post to a larger size. I scaled the photo size down three times and its still the same each time. I brought it up in an old photo shop first so I can alter it just not sure what it is supposed to be and lots of choices and could not find instructions, I thought there was a box that allowed us to change the photo size once we inserted it as well?

[Warren Lake]

so inserting works different than I expected and maybe I didnt need to size it down twice though it would not let me put it in the first time.

Joe there is my end nut if that is the right term, to the side is a second one from another machine the one of the collets, one birdsmouth bit. Some of the birdsmouth bits I have have a carbide insert in them. Interesting about this machine I took this apart to clean it and found the bit would not insert properly. It may or may not show in the photo but the previous owners son had snapped off a collet inside the shaft and you can maybe see the part broken off inside. I didnt look right and I have a second machine so opened that up and could see right away. When I pulled it out it came out in four pieces no damage and all was fine.

[mreza Salav]

Your photo shows fine Warren. I see the chuck has a collet, I suppose it should have better grip on the bits.

[Warren Lake]

yeah thanks I was typing while you posted. above someone mentions about resistance on plunge cuts. When I used to do a fair bit of router hogging in the past and had to plunge in I used to use a two flute carbide bit and just grind steel away, then it would plunge easily even if it was a bit not meant for that, later I discovered the single flute bits that were made for plunging. I already had a fair number of double flute bits so I just would put them on the grinder and remove steel and angle into the carbide sometimes on a green wheel. I havent tried any of these but if I was experimenting now i would take some of my old long two flutes and see how they plunge in as well. The worked well in the router for hogging and maybe for this function as well.

[Joe Calhoon]

Hi Warren,
Table looks the same as my late 70s 2000D Linvincible. About the first year of the SCM tan color. Like I said mine came with the Wescott chuck. I wonder if the collet chuck is original.

The table stops were not so good on this machine so I made a aluminum sub table with holes drilled to accept steel dowels for stops for different width rails. And spacer blocks for the side to side movement inserted to match the rail width. We built lots of loose tenon doors with this setup.

[Warren Lake]

Have two both are 100 percent original from original owners from Cooper and Horton in Toronto. I probably have years and original paperwork just forgotten memory wise. nothing was changed on either machines though one has had the switches replaced.

Upload failed so lets try this again, someone tell me how you size this stuff ill do another smaller one. I guess a photo does not come up full size unless you link it to somewhere else?

wiring on that shot was temp after some issues I found all the internal wiring from that box to the switches was rotted and casings broken down just waiting to short out.



325703

[Denis Kenzior]

John,

I have a Wescott Chuck on my J/P Combo mounted mortiser. Same overall experience as you. With large bits, particularly if they have any sort of a spiral, the bit starts to self feed and can get loose in the chuck. Seems to be a real issue with bits 5/8" and above. One sage advice I was given was to adjust the ways on the mortiser table (particularly the in/out one) to be tighter. Gives you a bit more control over the depth of cut and lessens the chance of having the bit dig in too deep. I've made that adjustment and this has helped quite a bit, but you still have to watch it and go slow.

[mreza Salav]

how do you join a board with the attachment sticking out in front? doesn't it get in your way?
Resize the photo with a software (you can use simple paint) to be smaller then upload should work fine.

[Warren Lake]

So I responded to your post Joe and it shows I did when I open the site yet I go to page three and there is no post there. that makes no sense at all sorry if this shows up twice

Agree with you the table stop system was not well thought out, there are some primitive things on the machines still I really like them. wiring was temp on this photo I had a switch issue and traced all the wiring and the wiring from this box through the machine internally was in bad shape, the insulating casings on the wires had broken down at several points and was just waiting to short out.

Have two both from original owners both from Cooper and Horton in Toronto, collets are 100 percent the same on both machines. Both are green and ill have to check years as its not in the memory right now.

325705

[Mike Wilkins]

I have had a similar outcome with spiral router bits. A design that provides smooth top of the hole/mortise will have a tendency to pull into the wood stock. I have had bits work their way out of the collet; and the resultant gouge in my bench-top to prove it.

[John TenEyck]

Thanks Denis. Your comment about the larger bits getting loose is what makes me think a square shank would be a good solution. But there must be something wrong with that logic since I can't find any bits like that and if it were the correct solution someone would have done it by now.

The in/out ways on my mortiser are really stiff already. Same for the L/R ones. I'd actually like to figure out how to loosen them up a little because I have to wrestle with it to make it move but don't see any adjustments to do so. Anyone with a Mini Max mortiser have some knowledge about this?

John

[Jeff Duncan]

wiring on that shot was temp after some issues I found all the internal wiring from that box to the switches was rotted and casings broken down just waiting to short out.


325703

Those older SCM's had some crap wiring in them. I have an SCM shaper from about 69' and had the same problem, main wire insulation was literally crumbling off everywhere. The smaller gauge control wiring was just fine, but they must have had a bad shipment of the heavier gauges. Great old machines otherwise….built like tanks!

JeffD