I am trying to CAD up a drawing for a plate for this motor to mount to. I figured it would be easy since they provided an mechanical drawing, but I have never seen one like this before. Can you please help me read this? It is from China and I don't even have any idea what units it is in. I have read these before but I am completely stuck on this one. I am trying to figure out the spacing of the mounting holes on the front of the motor. Here is the drawing

enter image description here,

and here is a picture of the actual motor if that helps at all.

enter image description here

From what I can tell the mounting holes are on the bottom (or left if you rotate it). Any help is GREATLY appreciated. I can't continue my project until I get this figured out.


2 Answers 2


"I am trying to CAD up a drawing for a plate for this motor to mount to.".

I read the drawing and TinEye.com searched the photo.

For the "Star" bracket you'll need a 114.3 mm recess, 3.2 mm deep to allow for the raised inner section, with a greater than 22.23 mm through hole to allow for the shaft. The bolt hole circles are 106.4 mm and 149.2 mm diameter. Use 5/16" x 18 TPI bolts and 3/8" x 16 TPI bolts; the "Star" bracket uses all 8 bolts, the "L" bracket configuration uses only the 3/8" bolts. Of course you can combine designs and come up with your own.

Metric Conversion (rounded to nearest imperial measurement):

  • 114.3 millimetres = 4 1/2 inches

  • 3.2 millimetres = 1/8 inch

  • 22.23 millimetres = 7/8 inch

  • 106.4 millimeters = 4 3/16 inches

  • 149.2 millimeters = 5 7/8 inches

Here are example mounting plates for that motor:

Source: http://www.electricmotorsport.com/nema-143t-c-face-1-2-inch-aluminum-l-bracket-motor-mount.html

Motor Mount - L Bracket

Source: https://m.ebay.com/itm/Manta-10-hp-electric-motor-MOUNT-Etek-Briggs-Motenergy-Permanent-Magnet-STAR-NC-/391984038365?nav=SEARCH

Motor Mount - Star

Motor Mount - Star mounted on motor

If you are considering purchasing one of those brackets you can probably find the "L" bracket for a lower price since it looks easy to make and is priced fairly expensive at the place given in that URL. The "Star" bracket is more complicated and CNC machined, for a custom item it's price is more inline (and you may find it difficult to get someone to make you one for less).

Which of the two, or another design entirely, really depends upon what you intend to attach it to.

Those photos ought to give you a hint about how you want to draw it up and the appropriate dimensions to use. The place you bought it from probably has brackets, a drawing of the bracket might help you more than one of the motor.

  • $\begingroup$ Nice chamfering on the 8 location holes, then they use bolts with flat washers... some decent hex head bolts would be better and have the advantage of staying flush... $\endgroup$
    – Solar Mike
    Feb 25, 2018 at 7:45
  • $\begingroup$ @SolarMike - Yes, the engineering principles are grossly lacking; an insult to E.SE, but the basic shape will help the OP either with design or sourcing the part. The L-bracket seems no better, the extra holes are in case you want to rotate the orientation with twice as many choices. At least they have a fair reputation for motor winding. $\endgroup$
    – Rob
    Feb 25, 2018 at 13:48
  • $\begingroup$ sorry, did not mean to imply that was your work. $\endgroup$
    – Solar Mike
    Feb 25, 2018 at 14:58
  • $\begingroup$ @SolarMike - I didn't take it that way, and you are correct; why did the website advertising the bracket not shell out for the correct parts ... There are faults in each but we can rely on Mathew to do a better job ... $\endgroup$
    – Rob
    Feb 26, 2018 at 2:27

Bottom or left based on what datum?

It matters not, really. The end of the shaft visible in the photo is your mounting area. The drawing shows two sets of mounting bolt options. The inner circle formed by the holes in the first ring appear to be (surprisingly) SAE threads, 5/16" x 18 threads per inch, 10 mm deep. The second ring of bolt holes are showing as 3/8" x 16 threads per inch, 19 mm deep. A nice combination of SAE and metric (grin).

Other dimensions appear to be in millimeters, including the diameter of the raised center section of the motor plate at that end. Your mounting plate, assuming a flat plate mount, would require a center hole of 114.3 mm diameter to clear the boss of 3.2 mm thickness.

Considering that the 5/16" holes are in recesses of the boss, one either would not use those holes or would provide for 3.2 mm washers/spacers to fit in the recess. The bolt holes on the outer circle are quite hefty and should take a substantial load transfer, removing the requirement of using all eight holes for mounting.

  • $\begingroup$ Yes, metric dimensions but english threads... $\endgroup$
    – Solar Mike
    Feb 25, 2018 at 5:31

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