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Step 6Add holes for motor mounts
After welding the frame, some additional holes need to be drilled for secure mounting of the motor. First place one motor into the frame, and add a bolt through the front mounting pivot and the Motor support on the frame. Make sure the motor drive shaft is sticking out of the frame, and that the motor is over the Center cross member.
You'll see that the barrel end of the motor is over a cross member. Place your U-bolt over the motor and center it on the cross member. Mark the location where the two ends of the U-bolt are positioned on the frame. These locations are where the holes must be drilled. Remove the motor. Now, since there is an upper cross member that would interfere with drilling, the frame needs to be turned over. Before the frame is turned over, measure the locations of these holes from the side of the frame, then turn the frame over and mark the holes according to the measurements you just took (and make sure you're marking on the correct side of the frame).
Drill the hole closer to the center first. Now, for the second hole close to the frame rail, some care must be taken. Depending on the size of your motor, the hole may be positioned over a weld that connects the cross member to the frame rail. This was the case for me. This puts your hole over the side wall of the frame rail, making drilling much more difficult. If you try to drill this hole with a regular drill bit, the geometry of the cutting tip and flexibility of the bit will not allow it to cut through the side wall, but rather bend the bit away from the wall, resulting in an out of position hole (see sketch).
There are two solutions to this problem:
1. Drill the hole with and end mill, which has a flat cutting tip to remove the side wall (requires clamping of frame onto drill press or mill)
2. Drill the hole with a drill bit, then file the hole to the correct position using a round file (takes a lot of effort and time)
After both holes are sized and positioned, repeat this process for the motor on the other side of the frame.
You'll see that the barrel end of the motor is over a cross member. Place your U-bolt over the motor and center it on the cross member. Mark the location where the two ends of the U-bolt are positioned on the frame. These locations are where the holes must be drilled. Remove the motor. Now, since there is an upper cross member that would interfere with drilling, the frame needs to be turned over. Before the frame is turned over, measure the locations of these holes from the side of the frame, then turn the frame over and mark the holes according to the measurements you just took (and make sure you're marking on the correct side of the frame).
Drill the hole closer to the center first. Now, for the second hole close to the frame rail, some care must be taken. Depending on the size of your motor, the hole may be positioned over a weld that connects the cross member to the frame rail. This was the case for me. This puts your hole over the side wall of the frame rail, making drilling much more difficult. If you try to drill this hole with a regular drill bit, the geometry of the cutting tip and flexibility of the bit will not allow it to cut through the side wall, but rather bend the bit away from the wall, resulting in an out of position hole (see sketch).
There are two solutions to this problem:
1. Drill the hole with and end mill, which has a flat cutting tip to remove the side wall (requires clamping of frame onto drill press or mill)
2. Drill the hole with a drill bit, then file the hole to the correct position using a round file (takes a lot of effort and time)
After both holes are sized and positioned, repeat this process for the motor on the other side of the frame.
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Sep 8, 2009. 9:07 AMMajor Fuchs
says:
Hey i have a question. how much did this cost you. parts wise.
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3
Sep 17, 2009. 3:22 PM
rpantaleo (author)
says:
rpantaleo (author)
says:
This cost me about $150. But, I had the wheelchair motors, batteries, and steel for the frame donated. If you had to buy everything, it would run you at least $500 if not more.
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May 12, 2009. 2:46 AMDon.Jambo
says:
Hey man... What is the exact position(or coordinates) of the motor axle as you look the frame from one side? I have a different type of motor, and I have to build for it a different motor mount for it, and depending on the position of the axle I have to weld some extra tubes to the frame! Thanks! X would mark the exact position of the axle: _ _ _ _ _ _ _ _ _ _ _ _ _ | _ _ _ _ | X _ _ _ _ _ _ | PS I'll send you some pics with a how far I'm at with a replica of you robot!
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3
May 12, 2009. 7:47 PMrpantaleo (author)
says:
rpantaleo (author)
says:
The axle of the motor should be in the middle of the frame. Looking at your sketch, you need to move it towards the center. I'll try to get a pdf drawing posted.
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May 12, 2009. 2:47 AMDon.Jambo
says:
Can you mark it exactly in another sideview.PDF with SolidWorks?
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