Power Cord Replacement

[JPG]

I just encountered this thread for the first time and really am curious if 14 gauge wire was not what was designed with the 3/4HP motor back in the 1950's and was never revisited thoroughly when they went to 1 1/4HP motors.

Changes in start capacitors and circuits on the 1 1/4HP motors could have masked a good bit of symptoms with better starting and what you folks have discussed makes a great deal of sense as it shows up as IR Drop under loading. 12 gauge wire changes the curve fundamentally and your observations support that notion.

There is more torque through the power curve. The motor is capable, but the 14 gauge wiring introduces loading of its own that simply isn't present with 12.

Many have commented that their units run on the warm side. For those of you who have gone with 12 gauge wiring, have you noticed it reduced the heat build-ups?

Thoughts?

Everett

I think the belt/pulley/bearing generated heat is the more significant contributor to heat buildup especially at the idler shaft. I do not think a 14 Ga cord limits much, but a #14 extension cord or #14 building wiring does.

[hkp7fan]

I just finally got around to replacing the switch and power cord on my 1955-vintage Magna Engineering Shopsmith Mark V. It turned into an ordeal that took all afternoon. But I got it done.

I had called Shopsmith last year when my original switch failed, told them *exactly* what I had, and purchased the recommended toggle switch and replacement power cord. But I just limped along for a few months turning it on and off by plugging and unplugging it, until I finally decided it was time to take the plunge and install the replacement parts.

The instructions that came with the replacement switch were useless, not least because they contained an obvious misprint in the first paragraph. Someone had failed to edit properly, and had cut and pasted an earlier instruction right where it said "Set the speed dial to...." , so I had no idea - Slow? Fast? What? I could tell that other aspects of the instructions were also not relevant - part of the joy of working with my grandfather's Shopsmith.

Side note: When I first inherited the machine from my grandfather in 1990, I took the headstock to the Shopsmith Store in Detroit for an overhaul. They gave it to some kid to work on, and he tried to pry off the nameplate and broke it. There is no access port on those Magna Engineering machines, but they didn't know that. They didn't fix it, didn't apologize, and didn't even point it out until I asked why it was broken. Then they acted like it was *my* fault! So I have a bit of a chip on my shoulder about Shopsmith, and am always *very* careful to tell them *exactly* what I have, and to repeatedly ask them clarifying questions to help determine if they *really* know what they are talking about with respect to my vintage machine. Human nature being what it is, they sometimes claim to know but still don't really know. On with the story:

Since the instructions didn't match my machine, I started looking online. I watched some videos, including the Shopsmith maintenance and restoration DVD's I had bought. None were helpful. Then I found this thread and downloaded the instructions in the link above (below?). They seemed much closer to what I have, so I plunged in. Removing the cover and motor pan were easy. My original green power cord was ungrounded and had the round rubber strain relief. I got it out (had to cut the power cord to do it, as it was either molded on or just fused together by time and heat). I put on the new cord, and decided to ground it on one of the little bolts holding the motor housing together. (I hope that's a real ground - there is no designated ground connection on that motor that I could see). Then the trouble began.

The strain relief that came with the cord was hard black plastic and oblong in shape, with two rounded ends and flat sides. It was too big for the hole in the motor pan. No problem - the instructions said to enlarge the hole to 9/16". I had to go buy a 9/16" drill bit ($19) but ok, now I have it in case I ever need it for something else. After enlarging the hole, I quickly realized that even 9/16" was *way* too small. Long story short, I spent a very long time trying to enlarge the hole enough to fit that thing in. It was so tight on the power cord that I was worried it would damage it, so I even ground out a little bit on the inside of the plastic fitting to help it compress the (very hard) power cord. I ended up using a Dremel tool, file, pliers, and hammer, holding the pieces at all kinds of awkward angles and trying to fit the whole mess together. Finally, finally, *finally*, after much ungentlemanly cursing at the Shopsmith people, I got it wedged in there (well, the broken pieces of the strain relief are wedged in there together), and the cord seems secure.

Replacing the toggle switch was easy. I reassembled everything, and it runs fine, so I am satisfied with the result. But if I had it to do over again, I would not even *try* to fit that ridiculous hard plastic strain relief into the motor pan. I'd either build up the power cord with tape on either side, or else find some other strain relief piece (you can probably buy them someplace, but I didn't look). This was supposed to be a quick repair job so I could get on with the afternoon's project of using the flexible shaft and wire brush to burnish up a rusted metal sign my wife wants to display on our house. Instead, it *became* the afternoon project, and I was just washing up when my wife got home from work around 7 PM. But at least I can turn it on and off normally the next time I am ready to use it to do the actual work I wanted to do in the first place.

[chapmanruss]

hkp7fan,

Sorry to hear about your past experiences with Shopsmith. Someone at the old Detroit store didn't have enough knowledge to understand the differences of the Mark 5/V tools made over the years. In your case anything about the differences of the original "A" Headstock. Unfortunately, some of this is still true when it comes to Customer Service today. Those people answering questions at Shopsmith have the more current Mark V information and not very much experience with the older Shopsmith Mark 5 differences. Due to retirements in the last decade long time Shopsmith employees have been replaced with new hires. This leads to these unfortunate situations. Some of the best information on repairing/working on the older Shopsmith tools come from this forum. It has been my best source for learning about the older Shopsmith tools and has helped me become better informed about them.

As for your cord replacement I too have gone through the cord strain relief dilemma. The old Mark 5 Greenie did not have a grounded cord and therefore was a smaller diameter cord being two wires as opposed to three. That requires a larger strain relief and the larger elongated hole. This as you have learned is probably the most difficult part of the cord replacement job. The 3 page instruction linked in the first post is a pretty good explanation of the process but there are variables not covered. The cord strain relief used may not fit the 9/16" inch hole it recommends. I have found that out myself. I have restored 2 Mark 5 Greenies and a Goldie replacing the power cords on each of them. I have a second Goldie waiting to be restored which will get a power cord replacement. I know when I was enlarging the holes I wish I had a punch for the job instead of having to do the drilling, grinding and filing.

I recommend to anyone having questions about older Shopsmith Mark 5 and other tools to ask them here where there are people that have experience with these older tool versions. JPG for example has owned his 1960's Goldie Mark 5 since it was new. That's a lot of years of Shopsmith experience.

[DLB]

IIRC from the DIY PowerPro upgrade, the strain relief will fit in a 3/4" round hole as well as the standard punched hole with flat sides. (That's not very close to 9/16".) In the newer instruction video, Gen 2, Jim M demonstrates with a step drill bit.

- David

[chapmanruss]

Although installing the Power Cord Strain Relief in a round hole will hold it in place it can allow the strain relief to rotate in the hole. This can twist the wires inside the Headstock and could cause problems.