Shopsmith Forums

I just bought a replacement 1-1/8 HP Emerson motor from eBay to replace my existing one. I noted that there was no capacitor mounted to outside of my motor like my original motor. The eBay vendor couldn't tell me 1) if there's a start-up capacitor built inside the motor's casing or 2) whether these motors even require a start-up capacitor or not. He said he's never seen one with it.

Do you know if a capacitor is required to successfully start this motor? I've not hooked it up yet with fears of damaging something at startup.

My new Emerson motor model # is either C550DR15C or C55DDR15C (it is hard to distinguish the 4th character on name plate). See attached photo.

I attach photos of:

• my original motor (showing external capacitor hump)

• my new Emerson motor (w no external capacitor hump)

• nameplate from new motor

My old motor came off of a 40-year old Shopsmith knock-off machine called a WoodMaster Multi-Tool. They went out of business not long after I bought my brand new machine in 1981. It came with a Teco 1-1/2 HP motor in it.

NOTE: I've bought many replacement add-on attachments & parts from Shopsmith to work on my WoodMaster which worked out very well. The one exception that comes to mind is when I bought Shopsmith replacement sheaves. They came, naturally, with std American made English center bore hole that were 1mm too small for my Japanese/metric motor's shaft. But I got a nearby machine shop to rebore the center holes for me. It has worked flawlessly for over 2 years since then.

I look for your helpful replies.

The start capacitor for the Emerson is internal to the case. IIRC you can see it through the vents in the non-shaft end cap. From your post I could not tell if you were planning to use the bored out sheaves on this, I don't that is ideal.

- David

Tx for your helpful reply, David.

I am NOT reusing my bored-out sheaves. The new motor came with a pair of sheaves already pre-mounted on the shaft.

I will check out the "peep holes" to find capacitor tomorrow.

Usually these motor capacitors are pretty big (see photo of outside of my old motor.) I don't know how they pack such a large component into that casing.

I have another question related to this motor which I will post separately in next couple of days.

There are two types of motor capacitors; start and run, Replacement capacitors in general these days are smaller in size than the original.

Among other values, they are rated in a microfarad 'range'. Start capacitors have a higher microfarad rating than run capacitors. Because of that, run capacitors are smaller too.

Whether or not you have a run cap or a start cap is up to the motor designer...but you should establish which you have. If they're not faded, values are on the capacitor body itself.

Kevin

David,
I DO see the capacitor inside the motor's casing. Tx.

I have an additional question.

The shape of the motor casing's bottom is rounded on the new Emerson but my old motor & bottom half of head stock from the WoodMaster have a very flat bottom. (Please see photos from prior correspondence. You'll see what I mean.)

Also, the center-to-center bolt holes between old and new motors (to fit motor to head stock's bottom section) are different and new motor's bolts and related holes are much smaller.

I can drill new holes in the head stock's bottom to accept the new motor's bolt hole pattern and smaller diameter but am concerned a bit about the different bottom shape. My plan is to use a wedge-shaped piece of wood to fit the contoured motor bottom so it rests flat on the head stock's bottom.

It seems like the biggest issue is before drilling holes to be that the upper and lower sheave shafts are in alignment and that the upper & lower sheave pairs are in perfect alignment so that belt is not twisted.

How does that sound? Any tips on making that happen perfectly?

Might there be a issue in the vertical distance between the upper and lower shafts after putting in the wedge/spacer block?

What is the recommended center-to-center distance between the upper and lower shafts in a std Shopsmith?

For comparison, I will check that against my WoodMaster's set-up after I temporarily reinstall the old motor to get that dimension.

The difference between Shopsmith and WoodMaster shaft spacing may be slightly different because the Shopsmith's head stock bottom half has a rounded bottom contour (Fortunately, I have a Shopsmith Owner's Manual; but I wish I had a Mechanics Manual that gave all dimensions) where my WoonMaster's head stock bottom half is definitely flat on the bottom.(See prior photo posting.)

All advice in getting this correct the first time would be much appreciated. I am not a mechanic by nature but very good at following clear instructions.

Thanks much in advance.

Hey Kevin,

Good words.

I've been told that it was a start capacitor, but it doesn't really matter since David clarified (and I confirmed visually) that new Emerson motors have the needed capacitor built-inside the motor's casing.

ALarryAaron wrote: ↑Fri Apr 05, 2024 1:47 pm Hey Kevin,

Good words.

I've been told that it was a start capacitor, but it doesn't really matter since David clarified (and I confirmed visually) that new Emerson motors have the needed capacitor built-inside the motor's casing.

Thanks. My ramblings were centered on understanding replacement capacitors and how to negotiate the waters with what you will find available today.

I have a GE motor on my 10ER which I assume was the replacement for the original AO Smith motor. In any event, the GE motor was so old as well, that it's dropped off the radar for replacement parts. When I peeled the cardboard off the start capacitor, all the values were there EXCEPT the most important part; the microfarad rating. I took the capacitor to a motor rebuild shop next to(and a part of), NAPA. Two young guys who worked there couldn't help me. There were the beginnings of very faint characters in the microfarad range of the capacitor. I was able to 'guestimate' from what was there to something on the shelf new, that was half the size.

There is some math in this given the voltage, hp, motor type, etc. I tried to explain that to the young lions. Eventually, I was about to take home the capacitor I found when an older guy in the shop appeared and took us all over to a wall. On the wall are charts already done wherein you feed your motor specs into the chart and it shows the approved microfarad ranges of various capacitors....start & run. Turns out, I had picked correctly, even though the cap was half the size of the original.

Pretty cool to see that motor easily start again and have been using it since. Beforehand, I tore down the motor completely, cleaned/repacked the bearings, and removed any rust I found. In theory, I should have tested the armature and the field coil, but I did not.

Kevin

Curious what and with what you would have checked the run/start windings and what values you expected to observe?

JPG wrote: ↑Sun Apr 07, 2024 2:12 am Curious what and with what you would have checked the run/start windings and what values you expected to observe?

There are no lack of YouTube vids on checking field coils and armatures. Some of them are rubbish, but when you see the same procedure and advice over and over again, they are most likely accurate. Especially coming from large motor rebuilding shops etc. It takes some time on the armatures because you start testing the segments 180 degrees from each other and then next to each other......all the way around. Use a Sharpie or something similar so you don't lose your place.

There is math in figuring out run/start capacitor values, but it's pointless when there's charts out there for rebuilders.

Kevin

Armature, segments? We be referring to induction motors. Windings are very low resistance, and it only takes one short to make the motor unusable.