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Motor Strain Relief
Posted: Thu Nov 11, 2021 6:21 pm
by SteveMaryland
Just finished a headstock rebuild and wanted to replace the motor cable strain-relief bushing.
After much plier and screwdriver work I finally got the strain relief out but beat it up in the process so of course I wanted to get a new one. The original was made by Heyco. My pliers wiped off the old part number, but I found the current Heyco parts numbers - the spec sheet is attached. I think the correct Heyco part numbers would be 1487 or 1490. I could not determine from the Heyco spec sheet what the difference is between these two.
Shopped everywhere (Grainger, Home Depot, Bisco, Shepherd Electric) for days for someone to sell me this strain relief but no luck. So I wound up re-using the beat-up old one. Drat! I would be willing to use any other brand but the problem is that the feed-thru hole in the Shopsmith (mine is a 1987 Mark V) is lozenge-shaped not circular so whatever strain relief must fit this unusual hole.
I know this strain relief issue has been discussed before, but curious if anyone has used a Heyco 1487 or 1490 or whatever other brand successfully.
Re: Motor Strain Relief
Posted: Thu Nov 11, 2021 7:35 pm
by jsburger
SteveMaryland wrote: Thu Nov 11, 2021 6:21 pm
Just finished a headstock rebuild and wanted to replace the motor cable strain-relief bushing.
After much plier and screwdriver work I finally got the strain relief out but beat it up in the process so of course I wanted to get a new one. The original was made by Heyco. My pliers wiped off the old part number, but I found the current Heyco parts numbers - the spec sheet is attached. I think the correct Heyco part numbers would be 1487 or 1490. I could not determine from the Heyco spec sheet what the difference is between these two.
Shopped everywhere (Grainger, Home Depot, Bisco, Shepherd Electric) for days for someone to sell me this strain relief but no luck. So I wound up re-using the beat-up old one. Drat!
I would be willing to use any other brand but the problem is that the feed-thru hole in the Shopsmith (mine is a 1987 Mark V) is lozenge-shaped not circular so whatever strain relief must fit this unusual hole.
I know this strain relief issue has been discussed before, but curious if anyone has used a Heyco 1487 or 1490 or whatever other brand successfully.
AFAIK, the type of strain relief used in the SS motor pan is industry standard. The hole shape is not unusual. It is shaped that way so it will not rotate when installed. Round strain reliefs rely on a nut to keep them tight so they don't rotate after installation. The SS type is commonly called a grommet not a strain relief.
The strain relief used in the Shopsmith is very common and available. You don't need any specific brand. They are all pretty much the same. You just have to buy one for the gauge of cord you are using. In the case of the SS that is 14 gauge if the cord is original.
https://www.newark.com/c/cable-wire-cab ... ain-relief
Re: Motor Strain Relief
Posted: Thu Nov 11, 2021 7:42 pm
by JPG
Critical is the power cord dimension.
The Heyco has a small section that is squeezed to either install or remove it from the double d hole.
Unless that small section is moved inward(thus deforming the power cord) any effort/s is/are likely doomed to failure.
Re: Motor Strain Relief
Posted: Thu Nov 11, 2021 7:56 pm
by jsburger
JPG wrote: Thu Nov 11, 2021 7:42 pm
Critical is the power cord dimension.
The Heyco has a small section that is squeezed to either install or remove it from the double d hole.
Unless that small section is moved inward(thus deforming the power cord) any effort/s is/are likely doomed to failure.
But, that is the same as all brands is it not? It is not brand specific.
Re: Motor Strain Relief
Posted: Thu Nov 11, 2021 9:03 pm
by JPG
An old fogey like me only knows of the original hence I do not make any mention of those of which I have no knowledge.
Ya know an electric ice box is a frigidare.
A hex wrench is an Allen wrench.(except to those who own the trademark "Allen").
Re: Motor Strain Relief
Posted: Thu Nov 11, 2021 9:15 pm
by Majones1
I’ve seen these types of strain relief bushings on all kinds of equipment, from table lamps to ShopSmiths, and they are all a real bear to remove… until you figure out the trick of using channel locks (or special pliers made for this, but who has those) to squeeze the locking tab on the inner side of the equipment.
They are inexpensive, and can be purchased from many places, including Amazon. I have included a link to the Hayco page that discusses hole sizes for different gauges of wire. Also see a screen grab of a good search for options. Like John said, they certainly don’t have to be Hayco.
https://www.heyco.com/Strain_Relief_Bus ... f_Bushings
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Re: Motor Strain Relief
Posted: Thu Nov 11, 2021 9:22 pm
by jsburger
JPG wrote: Thu Nov 11, 2021 9:03 pm
An old fogey like me only knows of the original hence I do not make any mention of those of which I have no knowledge.
Ya know an electric ice box is a frigidare.
A hex wrench is an Allen wrench.(except to those who own the trademark "Allen").
Yup, that is what I knew it when growing up in the 50's.
The Frigidaire company was started in 1916 as the first electric ice box.
From Wikipedia:
"The brand was so well known in the refrigeration field in the early-to-mid-1900s, that many Americans called any refrigerator a Frigidaire regardless of brand."
Re: Motor Strain Relief
Posted: Thu Nov 11, 2021 9:51 pm
by DLB
SteveMaryland wrote: Thu Nov 11, 2021 6:21 pm
Just finished a headstock rebuild and wanted to replace the motor cable strain-relief bushing.
After much plier and screwdriver work I finally got the strain relief out but beat it up in the process so of course I wanted to get a new one. The original was made by Heyco. My pliers wiped off the old part number, but I found the current Heyco parts numbers - the spec sheet is attached. I think the correct Heyco part numbers would be 1487 or 1490. I could not determine from the Heyco spec sheet what the difference is between these two.
Shopped everywhere (Grainger, Home Depot, Bisco, Shepherd Electric) for days for someone to sell me this strain relief but no luck. So I wound up re-using the beat-up old one. Drat! I would be willing to use any other brand but the problem is that the feed-thru hole in the Shopsmith (mine is a 1987 Mark V) is lozenge-shaped not circular so whatever strain relief must fit this unusual hole.
I know this strain relief issue has been discussed before, but curious if anyone has used a Heyco 1487 or 1490 or whatever other brand successfully.
The part I have is marked Heyco 7P-2. I'm 99% certain it came out of a 2004 520 I upgraded to PowerPro. That maps to Heyco PN 1237, but it looks like it can be found on ebay under 7P-2.
Rounding out the hole would not be a show-stopper to me if it were necessary. When installing the DIY PowerPro the new hole is made round per the instructions. 3/4" diameter IIRC. I'm reasonably sure the kit includes the same strain relief and cord as a conventional headstock. Lack of anti-rotation is not noticeable.
- David
Re: Motor Strain Relief
Posted: Fri Nov 12, 2021 10:27 am
by edma194
JPG wrote: Thu Nov 11, 2021 9:03 pm
A hex wrench is an Allen wrench.(except to those who own the trademark "Allen").
I have a set of T-Handle Allen wrenches made by the Allen Co., which is just some trademark holder. Still call all the wrenches 'Allen', probably more recognized than 'hex key'.