DuginBR
off to a rocking start
Member since February 2017
Posts: 8
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Post by DuginBR on Mar 10, 2017 14:30:25 GMT -5
Inspired by other RTH members I decided to try my hand at making a flat lap. It has a 1/3 HP 1725 rpm motor and a plastic oil drain pan to collect the water. Being a rookie at building anything like this I wanted to keep it simple, so went with a direct drive system similar to what others have posted. The center well in the collecting pan is a water pond bulkhead fitting and the drain is a cooler drain attached to a hose. In addition to the rubber washer and nut that come with both fittings, a generous amount of silicon adhesive/sealer was applied to make sure they do not leak. A small pump supplies the water and a drip irrigation valve regulates the flow. The lap and pump are both plugged into a GFCI outlet. I tested the lap this morning and everything works well except for a couple questions, which I hope someone might be able to answer. 1. When ran with an 8” aluminum backing plate, the plate wobbled slightly. Not having used a lap before, I don’t know if this is normal, but if not, was wondering what might cause it? The motor is anchored to a 2" x 6" frame. 2. The shaft of the motor does not have a locking pin, so I'm wondering how to hold the arbor when tightening/loosening the nut holding the sanding disc. This morning I used pliers to hold the arbor but I’m concerned this will damage the threads on the arbor. Any advise or suggestions regarding these questions or anything else regarding the lap will be greatly appreciated. Doug
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Post by Drummond Island Rocks on Mar 10, 2017 15:43:13 GMT -5
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DuginBR
off to a rocking start
Member since February 2017
Posts: 8
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Post by DuginBR on Mar 10, 2017 17:51:13 GMT -5
Thanks Chuck. I will try another plate to see if that is the issue. Based on what you said though, I suspect it's the motor. It seems to run smoother when it's horizontal. When vertical it has a slight vibration and (for lack of a better term) oscillating hum. Will probably remount the motor horizontally and use pillow block bearings and pulleys as you describe. Will wait a few days though to see if there are other suggested solutions.
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Post by Drummond Island Rocks on Mar 10, 2017 18:09:09 GMT -5
Thanks Chuck. I will try another plate to see if that is the issue. Based on what you said though, I suspect it's the motor. It seems to run smoother when it's horizontal. When vertical it has a slight vibration and (for lack of a better term) oscillating hum. Will probably remount the motor horizontally and use pillow block bearings and pulleys as you describe. Will wait a few days though to see if there are other suggested solutions. There are motors that are built for horizontal mounting and motors that are built for vertical mounting. The bearings are different. Chuck
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Post by Drummond Island Rocks on Mar 10, 2017 18:48:01 GMT -5
a more technical explanation stole from a google source.
"Horizontal machines have bearings designed to hold the motor weight as a radial (vertical plane) loading, with accommodation for axial thrust as necessary. Vertical machines use different bearing systems, because the machine weight is now in the axial (vertical) direction, with tangential ("radial") loading created by the connected equipment and alignment. "
Watch these videos to show how to mount a horizontal motor to a flat lap
Chuck
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NDK
Cave Dweller
Member since January 2009
Posts: 9,440
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Post by NDK on Mar 11, 2017 10:18:09 GMT -5
To answer your other question, to tighten the nut on my lap (built basically the same as yours) I simply hand tighten the nut, then hold the lap plate & tighten the nut with a wrench. To loosen I do the same.
Is that a machined arbor you put on the motor? If not that could also be wobbly.
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DuginBR
off to a rocking start
Member since February 2017
Posts: 8
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Post by DuginBR on Mar 11, 2017 15:07:35 GMT -5
To answer your other question, to tighten the nut on my lap (built basically the same as yours) I simply hand tighten the nut, then hold the lap plate & tighten the nut with a wrench. To loosen I do the same. Is that a machined arbor you put on the motor? If not that could also be wobbly. I doubt the arbor is machined, at least nothing in the description that I see says so. It's a relatively inexpensive one sold on Amazon and Ebay Enkay 410-C 1/2" Motor Arbor - 1/2" Motor Shafts Grinder Buffer Polishing Wheel I'll check to see if the arbor wobbles without a plate, but am inclined to order a machined arbor regardless, like the one sold by Kinsley North. www.kingsleynorth.com/skshop/product.php?id=46850&catID=93Thanks for the info about loosening the nut and how easy it is when done properly. When I ordered the arbor I didn't check to see if it was left or right handed. The motor is wired for clockwise rotation, and the arbor is right handed. I was eager to test things (patience is not one of my virtues) so rather than taking the time to reverse the motor I used a lock washer to hold the arbor nut. It was relatively easy to tighten, but not to loosen. I suppose that's why it's called a lock washer. Thanks for the help.
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