Help - Cracked base on bench grinder

[dogzbody1]

I was quite happy to collect an 8 inch 3/4 hp Milwaukee bench grinder (model 5051) off of Craigslist last weekend. Runs like a top BUT I noticed this morning that the cast base is cracked. There are several cracks in the saddle area where the motor sits and one starting in the corner at the top the base.

The base is cast pot metal so no welding, given the number of cracks brazing is not likely a solution.

None of the online parts sources have replacement bases. Soooo

Does anyone out there have a spare base for an 8 inch Milwaukee or

Has anyone tried fabricating a replacement base say from 1/8 sheet metal?

I'm just starting my vintage tool collection, not a great start but challenges like this this is what makes it interesting.

Thanks for any help or advice that you can provide.
Steve

 

[drivesitfar]

Dogz: welcome to our group and sorry to hear your grinder has some issues. can you post up a few pictures of the cracks and of the model of your grinder so maybe we can help? i use the paperclip to attach pictures sort of like attaching a picture to an email and it's just above where you write your posts. there are other options, but pictures with some good writing are a lot easier to work with if you want the best ideas to fix a problem.

 

[dogzbody1]

Thank you for the reply, here is a picture of the saddle area, you can just see the cracks running between the bolt holes and in the corner of the base.

Not sure that this one can be saved but the motor runs great so a replacements seems in order.

 

[383 240z]

Thats very brazable. Id go with silver solder and call it good. Something like this. It's in the 1200-1400* range
http://www.zoro.com/harris-brazing-...gclid=CI2CjInYxsUCFQQWHwodK0kAcg&gclsrc=aw.ds

 

[drivesitfar]

Dogz: what is the dimensions of that piece you just posted? hard to tell from that little picture, but maybe some thick steel plate with a few holes tapped in it might be a good base for your grinder. if you are only able to post one picture at a time i'll have other members walk you through how to post more, but in the meantime post up more pictures of the base and of your grinder even if you take up 10 posts doing so.

if you have time and want more help the better the pictures and information will get you better help from us. are you able to braze or weld? 383 has one solution that might work, but i don't weld so i'll think of other solutions if i see more pictures and have dimensions.

 

[454ragtop]

If you're not up to brazing it as mentioned, might fabricate a steel reinforcing plate to sandwich the base between the plate and the motor housing. I doubt the crack in the corner would affect it in use, long as you didn't drop it or something.
HTH, Jim

 

[383 240z]

What are the 5 round holes for? the 2 large ones, I get, they save on material, the others look like they were melted by a torch of some sort. Could you post a side view? I'm guessing the top surface is curved? Keith

 

[dogzbody1]

Hi all
Thank you for the responses and great advice, I hope I can contribute soon enough.
I think the "extra" holes are simply casting imperfections, there doesn't appear to be any discoloration from heat around them. Here are some better pictures, I think it easier to see the multiple cracks running between those holes in the saddle area.
I am not a welder (a few classes many years ago but no residual knowledge I'm afraid).

 

[dogzbody1]

Another picture

 

[dogzbody1]

And a better one of the saddle

 

[The Cobbler]

as mentioned above, I think if you made up a plate to sandwich the housing & motor you would be good to go for the rest if your life

 

[gorilla]

Thats very brazable. Id go with silver solder and call it good. Something like this. It's in the 1200-1400* range
http://www.zoro.com/harris-brazing-...gclid=CI2CjInYxsUCFQQWHwodK0kAcg&gclsrc=aw.ds

I want to see the results of you trying to braze pot metal. I've seen some low temp solders sold at car shows that work with a propane torch., Usually they are messing around with beer cans, etc. They claim that the rod will work on pot metal I can't confirm that. the best bet might be an epoxy.

 

[ssdave]

I'd make up a thin sheet of steel to match, and then epoxy it to the pot metal. I think that would keep it together for it's lifetime. Easy to grind the edge of the steel sheet to match the base once it's set in place. Could even use a few small countersunk head bolts through the steel and base metal to hold it in place in addition to the epoxy. Again, can grind the heads flush once the whole thing is set up.

dave

 

[DenisG]

I doubt that it's pot metal (zinc-based alloy). More likely it's cast aluminum.

 

[dogzbody1]

Is that any easier to braze?

(Thanks for all the help!)

 

[rsanter]

I'd make up a thin sheet of steel to match, and then epoxy it to the pot metal. I think that would keep it together for it's lifetime. Easy to grind the edge of the steel sheet to match the base once it's set in place. Could even use a few small countersunk head bolts through the steel and base metal to hold it in place in addition to the epoxy. Again, can grind the heads flush once the whole thing is set up.

dave

This. Make the plate and epoxy it to the existing base.
Fill the unused holes with epoxy as well while you are at it

Bob

 

[383 240z]

I'd make up a thin sheet of steel to match, and then epoxy it to the pot metal. I think that would keep it together for it's lifetime. Easy to grind the edge of the steel sheet to match the base once it's set in place. Could even use a few small countersunk head bolts through the steel and base metal to hold it in place in addition to the epoxy. Again, can grind the heads flush once the whole thing is set up.

dave

This. Make the plate and epoxy it to the existing base.
Fill the unused holes with epoxy as well while you are at it

Bob

Agreed. The cast AL would be easy to TIG but I'm with the above posts. A good scuff with some 36 grit, same for the steel plate. You will need that "tooth" for the epoxy to bite into. Should outlast you. Keith

 

[drivesitfar]

Dogz: maybe the best solution that i don't think has been mentioned yet is to find a donor stand from another grinder that is cheap or not working. how does your grinder work except for the busted stand?

i'd also suggest looking for and buying a Craftsman block grinder because as soon as i find a 3/4 hp or 1 HP commercial one i'm selling my baldor because the blocks are almost bulletproof.

good luck

 

[DenisG]

Just another opinion: maybe you can find someone who can TIG aluminum motorcycle engine parts. Someone known to a motorcycle repair shop.

 

[zkling]

First off, determine if it is a weldable alloy. I have a feeling it is a pretty junky aluminum alloy, meaning welding will be difficult if not impossible, and that is coming from someone that has welded quite a few different aluminum castings. You can do a number of tests, but I would start by calling Milwaukee, talk to a engineer and see if they can produce a material spec for you. They have it document somewhere. Or if you are more of a trial by fire type, have someone strike it with a tig torch and see what happens. If it puddles it is most likely weldable, if it pops and fizzes, that will be an indicator of high zinc content.

 

[DenisG]

First off, determine if it is a weldable alloy. I have a feeling it is a pretty junky aluminum alloy, meaning welding will be difficult if not impossible, and that is coming from someone that has welded quite a few different aluminum castings. You can do a number of tests, but I would start by calling Milwaukee, talk to a engineer and see if they can produce a material spec for you. They have it document somewhere. Or if you are more of a trial by fire type, have someone strike it with a tig torch and see what happens. If it puddles it is most likely weldable, if it pops and fizzes, that will be an indicator of high zinc content.

You're right about seeing if it puddles under TIG but, I'll bet that it's an aluminum alloy that they commonly use for their tool castings/parts. I don't see a reason why they would go out of their way to use an inferior alloy when they have sources for something they commonly use.

 

[zkling]

Well to solve my own lunch curiosity. Did a little digging and found out it was produced by Modern Metals Foundry, for Wissota in turn for Milwaukee. Engineer there stated it is most likely either 319 or 356 both which are very weldable. In house they use 356 rod. I'd probably use 4943 or 4043 just for convenience sake.

 

[exmaxima1]

i'd also suggest looking for and buying a Craftsman block grinder because as soon as i find a 3/4 hp or 1 HP commercial one i'm selling my baldor because the blocks are almost bulletproof.

Seriously? You'd favor a Block over a Baldor? I like Blocks, but Baldors run so silky....

BTW, what Baldor are you willing to pass on?

 

[rancherbill]

zkling, your extra effort is awesome.

My question is why this happened. Is the motor smooth running? It has obviously been vibrating probably because of a bad wheel. Is there damage to the bearing or bushing? If it's good, I'd epoxy it and call it good. If the motor is not smooth it will break again.

 

[dogzbody1]

Thank you all for the great advice, and for going out of your way to find out what it was made of (Wissota didn't have any information). I'll try to find a shop that can have a go for me. The cracks may have happened because there was no base plate and it had only one of two bolts intended to hold it to the base (how I bought it - lesson learned). I'll look for a shop on Saturday and let you know what I learn.
Steve
PS rancherbill - agree, the extra effort is awesome,