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Discussion Starter · #1 ·
I got a bench grinder on CL. It has 13mm arbors, which are just slightly too big (0.519") for 1/2" (0.500) holes on most grinding wheels.

I could get a grinding wheel that comes with an arbor adapter and drill it out, but I'm wondering if there is another way. Any suggestions?

Here's my thoughts so far, let me know if you got a better idea:

1. I have a lathe and metric drill bits. I'm concerned that the plastic arbor will just get deformed when I put it in the lathe chuck, even if I just lightly tighten it, that it will get spun around by the 13mm drill bit if it's not held properly, and the wall will be really thin (just over 1/64").
I haven't bought new grinding wheels so I don't know how hard the plastic is. I was going to buy Norton ones that come with an adapter.

2. I thought of making a metal (aluminum) adapter for the next hole size up (usually 1").
 

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Grinding wheels are notoriously off-balanced and trying to ream one out is only asking for trouble. I would look for the correct size wheel or sell the grinder on Craigslist and start over.
 

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If you choose to "fill the gap" of the holes I would use something like Delrin or the other dense hard plastic products. They are inexpensive and available at the big box stores and can be sized on a lathe. Even drilled out metal would be subject to slipping so a spot of epoxy might help.
 

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Jeff, could you get a grinding wheel with a larger hole and turn a spacer out of a hard wood such as purple heart or IPE on you lathe and drill a hole the right size? Make a couple of three for spares.
Herb
 

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I agree with Art about reaming the hole on a 1/2" wheel. Out of balance wheels can fly apart with stress and wheels flying apart have killed people. A safety rule about using grinders is never stand directly in front of them as they are coming up to speed.

I would check Banggood to see if they have wheels with the right size center. They deal in mostly metric sizes. Ebay is another place to try and ebay UK or Australia might be better than the US site.
 

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They make an adapter, I see them all the time at Home depot. Freud sells one, or perhaps it was Ryobi, regardless, they sell them at HD. Look in the grinding discs area, usually will be there.
 

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Discussion Starter · #7 ·
I got some 1" diameter nylon bushings at Home Depot and drilled them out to 13mm on my lathe. They fit nice and tight on the grinder arbor. Now I need to get some wheels with 1" diameter arbors.
 

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They make an adapter, I see them all the time at Home depot. Freud sells one, or perhaps it was Ryobi, regardless, they sell them at HD. Look in the grinding discs area, usually will be there.
To adapt from 13 down to 1/2"? I've seen lots of various adapters to go up in size but not to go down.
 

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I have a Rikon Slow Speed grinder and I bought a CBN wheel. On regular wheels you can use a diamond Tool to make them round but with CBN you can not do anything about the wheel being out of round, or should I say the shaft of the grinder turning out of round. I had a very hard time getting the Alum Oxide wheel on the left side to ever rotate even close to round. I finally ordered some new washers from Craft Supply USA to get the Alum Oxide wheel to quit wobbling. Some grinders will never turn true no matter how many adapters or washers you put on them. So after you get this grinder adapted to a 1" wheel you may still not have a stable turning wheel.

Remember to wear a face shield when grinding. I went to work for Eastman Kodak in 1980 and they had long 16 week classes to attend as part of your basic training. One of the first things they made us do was to watch an industrial film about a man side grinding a drill bit and the wheel shattered and parts of it went into his eye. They showed the actual surgery to remove parts of the wheel. Needless to say that made an impression on me and it should make one on you. Those little plexiglas square over the wheel are not sufficient to stop a shattered grinding wheel. Plus if you read the instructions on most grinder wheels and grinders they specifically say not to use the sides of the wheel to grind on. Now must people use the side of the wheel but that stresses the wheel much more than grinding on the flat surface of the forward edge. Dont take your personal safety for granted. Be safe and you may still get injured but the injury will be less severe if proper precautions are used.
 

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Be sure to test your grinder wheels for cracks. Suspend your wheel by a wire or a round screw driver through the center hole. Thump the wheel and you should hear a clear ring and the ring should continue. If you thump the wheel and it makes a dead sound with no ringing the wheel may have a crack and should not be used. Each time you remove and replace the wheel be sure to test it and see if it rings. I take my 6" wheels off quite often to put on my brass brush wheels to clean up metal and usually replace the alum oxide wheel when done. I always test the wheel. Additionally if you drop your wheel check it both visually and through the sound test. A new wheel may have dropped many times before it got to you.
 

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Thank you Guy,any safety advise is good advise. I once heard of a bench grinder wheel shattering & a piece hit the corrugated iron wall with such force,it went right through.As Charles said,people have been killed . Jamesjj777746
 

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To adapt from 13 down to 1/2"? I've seen lots of various adapters to go up in size but not to go down.
FYI, not sure this helps, but these are the what you like to call them. I was speaking of.
Depending on style of disc, or accs. he plans on using with grinder. There are a few styles to choose from.
These or these, Both are at HD in the grinder area (usually under the freud and or Ryobi branding (for that store)
https://www.amazon.com/Reducing-Bus...nder+adapter&qid=1569223063&s=gateway&sr=8-15

https://www.amazon.com/OD3-1-Grinde...jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

Perhaps I am wrong on the matter, but we are talking about a 1/16~1/32 of an inch. Actually in mm, it is 0.3mm
 

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Brian he wanted to go from 13mm to 1/2". 1/2" is smaller than 13mm by that .3mm. You can't use a bushing to go smaller, only larger.

He got a bushing to go up to 1" and is going to try and find wheels in the right OD and ID that way. The only other viable option is finding 13mm ID wheels.
 
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My thought too,is to go with a larger ID wheel and make /buy a reducer bushing to fit on his lathe. Another thought is to remove the arbor from the motor and set it up in his metal lathe either between centers or chuck one end, turn down the other,and vice versa. He is only looking at taking off .15mm to make it work.

Just a suggestion.
Herb
 

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My thought too,is to go with a larger ID wheel and make /buy a reducer bushing to fit on his lathe. Another thought is to remove the arbor from the motor and set it up in his metal lathe either between centers or chuck one end, turn down the other,and vice versa. He is only looking at taking off .15mm to make it work.

Just a suggestion.
Herb
agreed, but I wouldn't use a chuck, unless it's a cnc chuck, because they are very inaccurate. I'd use a collet instead of a chuck. or between centers..:wink: also, regarding the plastic reducers, you can take light cuts at a time with a boring bar, and get good results.. it's better to make your own, and chuck up the solid portion of the plastic or aluminum, and bore out and turn to the sizes you need then cut it off..:smile:
 

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I agree with all you said, I was thinking of setting up with a 4 jaw chuck and a dial indicator (old school) to get the shaft centered correctly, I know that 3 jaw chucks are known to not be accurate. The last option you give sounds to me the best way to go.

Herb
 

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I agree with all you said, I was thinking of setting up with a 4 jaw chuck and a dial indicator (old school) to get the shaft centered correctly, I know that 3 jaw chucks are known to not be accurate. The last option you give sounds to me the best way to go.

Herb
I've made many thousands of parts for military applications, and know what works.:wink:
 
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