Reversing a Shaper, Jam Nuts, and Lock Washers

For safety, make sure the shaper head is firmly attached and can't work loose. February 22, 2011

Although I have been working in my shop for many years, I have only recently developed a need for a shaper. I purchased a used Polish shaper DFDA-4 and have cleaned it up into working condition. It appears to be a well built machine, but I haven't been able to find out much about it. From the web, I have determined that it must be marketed as a Unitronix brand. They didn't bother to put that on the machine.

Does anyone know where I can get parts for that machine, such as a manual, and maybe some additional spindles?

I hate to ask this next low level question, but in building musical instruments, I haven't needed a shaper. If you run a shaper in reverse, do you need a spindle that has left hand threads so the nut does not come loose? Or do you use a second nut as a jam nut?

Forum Responses
From contributor R:
I can't help with the first part, but as for running the shaper in reverse, I've never had an issue with the stock nut setup. Typically with a shaper, there is some form of spindle lock (or second wrench) that allows you to tighten the nut fully. This is needed to keep the head from spinning on the shaft in a cut. I've never had any issue with the nuts coming loose.

From contributor J:
Yes, use a jam nut! This is a safety issue. You should use a second nut on a shaper spindle regardless of which direction it's turning; you do not want to take any chances of the cutter shimmying.

From contributor D:

Do not run the shaper in reverse without a locking washer. The locking washer has an internal tooth that fits in the groove in the spindle to prevent the washer from rotating on the shaft. The nut is tightened up to contact that washer, with spacers, cutters, etc. below.

If you think of the physics, the cutting forces will want to rotate the cutter in the direction of loosening the nut, and things will spin off and create havoc or worse. Of course, one can envision a huge spindle and nut, torqued down to 200 ft/lbs, and a little bitty cutter doing a 1/8" roundover - unlikely the nut comes loose. But the opposite situation - large cutter, heavy cut, certainly will risk life and limb.

Not all shapers have this groove in the spindle, but some have been converted to spin CW. A second nut or jam nut is believed by many to be adequate, but the engineers on this say no - the anti spin washer is the only way. It would be simple to have a machine shop groove the spindle for you and make a couple of washers if this is a feature you will need.

As for your first question, I don't know of a current importer. The Ease European stuff was often sold like the Chinese stuff today - made with no label, sold to an exporter and then labeled by them. This means a machine shop is the place to go to have spindles or parts made.

From contributor R:
Contributor D, thanks for the info. I've worked with a number of shapers over the years and never encountered one without the lock washer, so your explanation is valuable. I have also read the manuals for those I have used, none of which mention a jam nut for reverse use. Now I know the real reason why.

From the original questioner:
Thanks for the valuable information. It makes very clear sense. I will be having a groove and lock washer made before running in reverse.

From contributor J:
Good answers here, though I have a couple questions for you. Does your shaper have a reversing switch on it already? And is it in need of any additional work which would require you investing more money into it?

You have a no-name machine and may not be able to find parts in the future. Is it worth your while to invest in having this machining done? There are many used shapers on the market with well known names that will come equipped with reversing switches, grooved spindles, and readily available parts. Something to think about before going any farther with your machine.

From the original questioner:
The machine did not come reversible. I have seen photos of this model machine with a reversing switch. No big trick to add the reversing solenoid though.

I understand your thoughts about putting money in a no-name. However, I have hardly anything in it. Bought it, and Felder AD741, Inca bandsaw, Inca jointer, RBI moulder, Ross 26" thickness sander, and a pile of Festool hand power tools and vac for $3700. All stored in a barn with a bit of surface rust, but easy to clean up.

All I really wanted was the AD741 initially, but am kind of getting attached to the shaper. Have a friend with a machine shop, too. It would be nice to find a locking washer for another machine (1 1/4" shaft), so all I had to do was mill the slot.

From contributor D:
Try this for the washer: go to McMaster-Carr and look up part number 94190A280. They have several sizes, in packages of 10.

From the original questioner:
Cool... I should have known that!

Does the groove typically go just past the threads, or most of the way down the shaft?

From contributor D:
Just past the threads. You want that tabbed washer to be directly under the nut - in contact with it - to prevent untightening. There is no need to have the groove run further down the shaft since the nut won't go there anyway.

From contributor M:
Just for laughs, let me share a little bit of information about the company that imported the Unitronix brand machines into the country. They were originally branded as Polamco. It stood for Polish American Machine Company. They were based out of Chicago. I bought a Polamco 16" jointer and a horizontal boring machine in the late 70's. They were not bad machines for the money. Plenty of cast iron and machined much better than the Chinese stuff coming in today. Now this was back when we were still in the cold war with the Russians, and one day I'm reading the paper and there is a story about a spy ring composed of a Polish machinery dealer out of Chicago being busted by the feds. You guessed it, it was the Polamco guys. The machinery still kept coming in, but the name changed to Unitronix. I wouldn't be surprised if there still isn't a dealer out there somewhere that has parts or sells it.

Everyone likes to make jokes about Polish stuff, but my experience with the stuff was pretty good. I ran the jointer for 20 years before getting a new one, as well as the boring machine, so you didn't buy a lemon. Contributor D certainly answered your questions about running it in reverse. Hope this adds just a little more info about your machine.