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View Full Version : Is this new grinder safe ?



mototed
02-23-2008, 08:45 PM
Just gat a new HF tool grinder. This one http://i217.photobucket.com/albums/cc28/mototed/IMG_0721.jpg
I ground a few bits on it, and it was a tad out of balance as it slowed down and you could see that the backing plates for the wheels wobbled a bit. I took the right backing plate off , thought I might try to true it up and the casting was full of fractures. http://i217.photobucket.com/albums/cc28/mototed/IMG_0722.jpg
Think it's safe ? After looking at the post about that gross lathe accident I was thinking about a 2 pound grinding wheel flying off @ 3200 RPM.
I Know that you get what you pay for, I've been trying to buy the good stuff but $700.00 US for a grinder for the house !

If you think this is a good casting what would be the best way to true these up? On the lathe, or in place on the grinder?

aboard_epsilon
02-23-2008, 08:51 PM
if that's aluminium ...
Ive see those marks before ...and they ain't fractures ...they are just the way the casting came out ...mold marks from contraction.
if you skim it a bit ...and they disappear ..this will verify.

yeah stick it a four jaw on the lathe ..

when you've finished make sure there is still a central raised boss ...

and don't take so much off ...that you run out of threads on the grinder arbour ..when you put it back on .

all the best.mark

Fasttrack
02-23-2008, 09:22 PM
Yeahl, I agree with Aboard Epsilon - i think those aren't fractures at all but you could put it in a 4-jaw and then indicate off of the bore, provided its a fairly tight fit. Sometimes you'll find that the hole is made over-size for ease of assembly but then when you tighten the setscrew on the key it pulls the wheel off of center so it vibrates. In which case, truing up on the lathe won't help.

As long as its a snug fit without the key in it then you can true it up on the lathe, otherwise it should be done on the shaft.

mototed
02-23-2008, 09:47 PM
I just sort freaked out when I saw those fractures. They where running all the way towards the holes, sort of like the way concrete cracks out from outside corners.

Uncle O
02-23-2008, 09:56 PM
Why not just whip yourself up a new one ? It would eliminate all doubts......

lazlo
02-23-2008, 09:58 PM
My backing plates looked almost as bad. It really improved the wobble and vibration when I turned the cast back part smooth.

garyphansen
02-23-2008, 11:06 PM
If you want to pay for the postage both ways, I will true it up for you for free. Just PM me and we will work out the details. Gary P. Hansen

mototed
02-24-2008, 07:40 AM
Thanks for the advise and offers of help (Gary) I'll mess around with it today and see what happens.

rwf71
02-24-2008, 09:09 AM
Those backplates are die cast alum. The "cracks" were in the die. If you run your finger nail across them you'll find they are raised from where the alum flowed into the cracks in the die. If the cracks were in the casting your finger nail would fall into the crack in the part. I have a lot of experience with alum diecasting and this is very common. Just true 'em up , "cracks" will dissappear & they are safe. Rick

quasi
02-24-2008, 04:31 PM
boy I wish someone would sell them in Canada for a Harbor Freight type price.

mototed
02-24-2008, 05:46 PM
I took it all apart.Started on the right side, turned the wheel holder disks thingings true then proceeded to the left side. WARNING, DANGER DANGER. If you buy one of these check all of the wheel mounting bolts, I unscrewed the the left side with my fingers, two screws were not even seated.:eek: Everyone is correct about the fractures, They where only "skin" deep. The machine is still a little out of balance, I'm thinking the wheels are warped slightly. When I draw the mounting bolts up they warp al wheel holders a bit. Right now it's working fairly good. I had a normal old 6" bench grinder that I'd mounted a warped wheel on (my shop is in the basment) If you need a new grinder, run one like that for about 1/2 an hour and the wife will beg you to buy a new one. It shook the whole house. I need a wheel for HSS. Anybody know the part# from Enco?
Thanks
Ted

aboard_epsilon
02-24-2008, 05:52 PM
do a bit of grinding or diamond the edges of the wheels ...

this may fix the problem.

all the best....markj

DICKEYBIRD
02-24-2008, 06:09 PM
I bought an AO wheel from J&L and a diamond wheel from CDCO for mine. Even the J&L wheel was grossly out of balance until I trued it with a diamond point dressing tool. I had to do the inside and the outside before it smoothed out. The stock mounting bolts were very loose on mine as well!

http://catalogs.shoplocal.com/jlindustrial/index.aspx?circularid=11555&itemcount=0&loggedin=false&newbanner=true&jlpass=1371&storeid=1038424&pagenumber=1375&fsid=1375 You'll have to grind the guard a bit to clear the wheel.

http://www.cdcotools.com/index.php Go to "Machine Tool Toolings" then "Grinding Machine Tooling." I bought the medium grit diamond wheel which is actually pretty fine. It leaves a great finish for sharpening existing tooling but would be fairly slow for making carbide tools from scratch.

I had to make an arbor to true up & reduce the dia. of the stock hub to fit the diamond wheel but the thing that REALLY pi$$es me off is the dang flexible lamp shaft. It's too wimpy and flops around. So far all the tricks I've tried haven't worked. Funny, I don't mind all the machining work I've had to do on it but the lamp thing infuriates me.

lazlo
02-24-2008, 06:15 PM
The stock mounting bolts were very loose on mine as well!

The stock mounting bolts are frightening. They're cast aluminum, probably so they can broach the hex head into them. On mine, there's not a single bolt out of the 8 where the hex heads are anywhere near the center.


You'll have to grind the guard a bit to clear the wheel.

I didn't have to grind my wheel guards.


the thing that REALLY pi$$es me off is the dang flexible lamp shaft. It's too wimpy and flops around.

Yeah, mine has E.D. too.

Fasttrack
02-24-2008, 08:28 PM
Silicon carbide is a nice wheel for HSS, in my opinion. I rough stuff out with AO and then the final grinding is done on the SC wheel. It leaves a nice shiny finish :)

Every new wheel needs to be dressed. The wheels i got were high quality wheels and they still need to be trued to the grinder to eliminate vibration.