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Thread: Macson surface grinder
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23rd Oct 2015, 12:51 PM #1Senior Member
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Macson surface grinder
New Machine
Does anyone have any info on the Macson surface grinder, apart from what has already been posted. I was interested to read CGroves thread on rebuilding his grinder, however there hasn't been any updates for a while.
Cheers
Peter
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23rd Oct 2015, 06:40 PM #2Senior Member
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Okay I have another question.
The x axis drive shaft has heaps of radial play, I removed the shaft and found that the section of the shaft that runs in the brass bush is smaller in diameter than the rest of the shaft (0.56 compared to .62")
It would seem that something is missing rather than just worn.(the brass bushing does have some wear)
Does anyone know what the correct setup for this is? Should it have a split bushing? If it is a split bushing what material should it be?
Cheers for any ideas
Peter
image.jpgimage.jpgimage.jpg
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23rd Oct 2015, 07:43 PM #3Most Valued Member
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Hi Peter,
By any chance is the bronze bush housed in an eccentric carrier? While no too SG are the same, the X axis handwheel on my Elliot passes through a bronze bush and the bronze bush is housed in an adjustable (eccentric) carrier. The eccentric can be adjusted to allow for wear (I assume) in the ways which would bring the rack closer to the pinion. The bush also has quite a generous amount of play to allow for the eccentric adjustment. Actually, I just realised it's not a bronze bush but a needle bearing but none the less the same deal.
To answer your other question, probably a phosphur bronze bush. They are available at most bearing suppliers for about $10, or you can make your own if you have some spare stock laying around. Actually if you find that the shaft is worn, then if you wanted to get crazy then you could clean up the shaft on the lathe and then make a matching bush for it.
SimonGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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23rd Oct 2015, 08:40 PM #4Senior Member
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Simon
Thanks for the reply. There is no eccentric for adjustment,( however the bushing in the housing is worn eccentric). The shaft isn't worn much at all, the issue is to take up the clearance, it would require something like a split bush within the bush in the housing (to fit the bush on the shaft it would need to be in two pieces, due to the reduced diameter on the shaft)
Not sure this is a good explanation.
Cheers
Peter
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23rd Oct 2015, 08:54 PM #5Senior Member
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- May 2012
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Hi Peter,
I see you are in Melbourne. Not sure if this will help but there is one for sale at Apex Machinery, if you wanted to have a look at another one.
Joe
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23rd Oct 2015, 08:56 PM #6Philomath in training
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I had the front bush missing on my power and replaced it. I think in a case like this you do what seems sensible, so if a split bush looks like the best option then give it a go. You do need something though to get a smooth feed motion.
Michael
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23rd Oct 2015, 11:54 PM #7Golden Member
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Hi Peter,
Here are some photos of mine (also apart for repairs). It looks like there are some differences - has four spokes on the capstan handle rather than three as seen on most, and a ball thrust bearing outboard of the bush.
IMG_0704.jpg
IMG_0705.jpg
IMG_0706.jpg
No sign of a split bush or step on the shaft where the bush bears, though there is a thin black dirt ring just inboard of the bush position. Maybe what you have is just a lot of wear on the shaft as well as the bushing. Building up the shaft may be possible by metal spraying.
Cheers,
Bill
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24th Oct 2015, 04:07 AM #8Senior Member
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Thanks for the photos and description of your SG Bill.
It is indeed a different setup to mine, especially the thrust bearing.
The step on my drive shaft where the bush bears appears too even to be wear, I am still thinking along the lines of a split bush. Not sure what material to make it out of though.
Cheers
Peter
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24th Oct 2015, 07:09 AM #9Philomath in training
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As the shaft looks like it is only pinned onto the handle hub, it could even be replaced with a step free version if that made making up a bush easier.
Bill's machine is an odd one as I can't think why a rolling element thrust bearing would be used - the handle is not moving at high speed and unless the gear at the other end is helical, there should be minimal axial thrust. For the duty and age of the machine I would have said a phosphor bronze bush (and a bit of grease) was all that was needed. As soon as a RE thrust bearing like that is incorporated there needs to be some sort of preload/ axial adjustment to keep it properly engaged as well as another bearing at the other end of the shaft to provide a reaction force.
Bill, what's at the other end of yours?
Michael
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24th Oct 2015, 10:28 AM #10Senior Member
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Thanks for your input Michael, I may go with your suggestion of making a new shaft, it would probably be easier/better than fiddling with a split bushing.
Cheers
Peter
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24th Oct 2015, 05:09 PM #11Golden Member
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Spot on Michael - helical gear, with ball thrust bearing which takes load when feeding against the grinding wheel, and plain bearing (steel gear against cast iron) for thrust in the other direction when "climb grinding" on the way back. The ball thrust bearing is a very basic affair with a pressed metal ball cage and two hardened plain washers for the races.
IMG_0707.jpg
Bear in mind that this machine was made for McPhersons at the famous machine tool factory of Filtration & Water Softening Pty Ltd in Melbourne.
IMG_7483.jpg
Cost control ruled out a second ball thrust bearing, but at least they were not stingy with the cast iron.
Cheers,
Bill
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24th Oct 2015, 07:44 PM #12Senior Member
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Once I removed the handle from the shaft and had a closer look (glasses on)
it was clear that the smaller diameter was a result of wear (you were spot on Bill) I am still amazed at the surface finish of the worn section.
I have repaired the worn section by brazing (nickel bronze) and have made a new bushing out of brass, maybe not the best combination but we'll see how we go.
thanks for your interest.
Cheers
Peterimage.jpgimage.jpg
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25th Oct 2015, 12:15 AM #13Golden Member
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Neat repair Peter.
The bronze on brass isn't ideal as a bearing combo but should buy you a fair bit of time.
Cheers,
Bill
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26th Oct 2015, 08:02 AM #14Most Valued Member
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Nice repair job Peter!
As for the combination of the two metals, well just see how it goes. It's not like it's turning at 3000 rpm! It will probably last forever in your shed. These old machines that get "re-birthed" by us are really in retirement now compared to their previous life and are unlikely to recieve any further wear compared to their previous life.
SimonGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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