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bunya pine
18th October 2016, 07:31 PM
Team
I picked up this little grinder however it's missing a left hand half inch nut to hold the grinding stone in place. I went to the local bolt factory and got an imperial half inch left hand nut and it does not fit. I ended up taking the grinder to the factory and they said they don't have one.

Is anyone familiar the threads that goodell Pratt used? And does anyone know where I can get a left hand nut for the grinder ?

Cheers

Stew

http://uploads.tapatalk-cdn.com/20161018/e135ebf4c710013f3a7776e19e92f8ee.jpghttp://uploads.tapatalk-cdn.com/20161018/08bdb23562757ce084d95c6c45dd921a.jpghttp://uploads.tapatalk-cdn.com/20161018/e0ddf67d872416db953dab3b5a2ca629.jpg

clear out
19th October 2016, 07:58 AM
Looks like a left hand thread?
H.

bunya pine
19th October 2016, 08:09 AM
It is

Oldbikerider
19th October 2016, 08:19 AM
I assume that you've measured the diameter at 1/2 inch? Short of using a thread gauge you can use a ruler and count how many pitches per inch. From that you have something to ask for if you can find somewhere that sells left hand nuts. Or find a machinist, or twist someone's arm here to make one.

Graham.

bunya pine
19th October 2016, 08:27 AM
I'm definitely more of a wood worker than metal worker :/

themage21
19th October 2016, 10:02 AM
I'd hazard a guess that the tpi and the even the pitch angle/thread profile might not be a standard imperial thread on that grinder. It's a nothing job for a machinist to make one (or a couple), but convincing one to do it may be your undoing.

Goodell-Pratt were bought by Millers Falls, which was in turn bought by Ingersoll-Rand and then looks to have been spun off and then taken over by a Chinese company. Given the dive that has occurred in the quality of the tools they make, I'd say that the intellectual property died around the time of the spin-off from Ingersoll. Which kinda kills the opportunity to email them and ask if they still have plans in a dusty cabinet.

I can't access it from my current internet connection (annoying blocks all over the place), but this may help: Restoring a Goodell-Pratt Hand Grinder - Lone Pine Toolworks (http://lonepinetoolworks.com/my-blog/restoring-a-goodell-pratt-hand-grinder)

Oldbikerider
19th October 2016, 11:14 AM
Yes, this is a pretty simple job. If Stew draws a blank on a source, I'll volunteer to make one. I'd need to check that I have some hex stock of the right size, and without a complete thread definition (dia. pitch, thread from, required fit) I'd need the shaft to fit the nut to. I'm located in northern Sydney.

Graham.

clear out
19th October 2016, 07:32 PM
I've probably got some hex if you haven't.
H.

hiroller
20th October 2016, 06:12 AM
Impressive looking grinder but I bet it would enjoy eating the odd finger or two!

Oldbikerider
20th October 2016, 07:15 AM
I've probably got some hex if you haven't.
H.
clear out, I found some 1 inch hex stock, so we're OK thanks. Stew is mailing the shaft down.

I think it needs a machined flat spacer to go between the nut and the grinding wheel. Can anyone suggest how this would have looked?

Graham.

camoz
20th October 2016, 12:02 PM
clear out, I found some 1 inch hex stock, so we're OK thanks. Stew is mailing the shaft down.

I think it needs a machined flat spacer to go between the nut and the grinding wheel. Can anyone suggest how this would have looked?

Graham.

Graham,

Unfortunately the image for the No.115 (which I think this one is) does not show the spacer, but I am guessing it would be similar to this one:

http://i1365.photobucket.com/albums/r754/woodworkforum/3B416307-E6F9-4DC9-9140-7AD6972862DB_zpscbgmrkhr.jpg (http://s1365.photobucket.com/user/woodworkforum/media/3B416307-E6F9-4DC9-9140-7AD6972862DB_zpscbgmrkhr.jpg.html)

cheers,

Camo

Oldbikerider
20th October 2016, 12:31 PM
Just a plain spacer then, same diameter as the wheel flange. Stew, can you measure the diameter of the flange. I'll make the spacer match.

Graham.

dennisk
20th October 2016, 02:32 PM
almost looks to me like beaten up Acme thread, possible? it is American.

Oldbikerider
20th October 2016, 02:53 PM
Yes, from the photo it could well be a square thread of some sort. I'll wait for the shaft, measure it up, then grind a tool if I need to.

Graham.

Oldbikerider
25th October 2016, 09:40 PM
Stew has sent the shaft to me, it arrived today. The thread is a 1/2" 13 tpi V groove thread, so it's 1/2" UNC. I have a thread cutting tool somewhere, just need to dig it out and get the nut turned.

Graham.

DSEL74
26th October 2016, 07:10 PM
Nice Grinder.


I'd suggest the outer flanged spacer would be a duplicate of the inside one which is present on the machine. There also is not always nut on all machines sometimes the flane has nut flats and sometimes there is also a jam/lock nut, all depending on mod and manufacturer. I'm not familiar with this particular one

DSEL74
27th October 2016, 05:30 PM
http://uploads.tapatalk-cdn.com/20161027/0fff1cddca6690841518fd37393ee356.jpg

Here is one with just a nut and washer
http://uploads.tapatalk-cdn.com/20161027/8ab463327b37407ae5ae3a1f12fd253d.jpg

But I think you will find this is what the original probably was.
http://uploads.tapatalk-cdn.com/20161027/04bc3034979e3a8c4de719817d056674.jpg

bunya pine
27th October 2016, 06:44 PM
http://uploads.tapatalk-cdn.com/20161027/0fff1cddca6690841518fd37393ee356.jpg

Here is one with just a nut and washer
http://uploads.tapatalk-cdn.com/20161027/8ab463327b37407ae5ae3a1f12fd253d.jpg

But I think you will find this is what the original probably was.
http://uploads.tapatalk-cdn.com/20161027/04bc3034979e3a8c4de719817d056674.jpg

Thanks for the pics and the add. The big question now will be if I strip and repaint the little grinder so it looks new like the one in the photo?

Cheers stew

Oldbikerider
27th October 2016, 07:38 PM
Stew, I've blanked out the parts, but yet to do the screw cutting. I've been off work crook today so they won't get finished until the weekend unfortunately.

DSEL74, it's useful to see those pictures, but this is a curious design. Both the backing flange and the nut are left hand threaded. The only way this makes any sense is if the backing flange is tightened hard against the small shoulder on the shaft, but the shaft doesn't appear to have been designed for that. Only Stew will be able to tell when he re-assembles it. And even then it's strange that they went to the trouble of making everything left hand threaded given that there are two tool rests on opposite sides of the wheel.

But whatever, I'm making up a nut and a turned flange, and these parts will get Stew out of trouble. I'll post pictures when it's done.

Graham.

DSEL74
27th October 2016, 07:42 PM
Not sure if I'm following you. On my other grinders the flange and the nut are one piece.

The is a flange on rack side of the emery wheel, only the outside one has spanner flats. There is usually a brass bush that sits inside the wheel to size the hole down to the thread bore.

bunya pine
27th October 2016, 07:42 PM
Stew, I've blanked out the parts, but yet to do the screw cutting. I've been off work crook today so they won't get finished until the weekend unfortunately.

DSEL74, it's useful to see those pictures, but this is a curious design. Both the backing flange and the nut are left hand threaded. The only way this makes any sense is if the backing flange is tightened hard against the small shoulder on the shaft, but the shaft doesn't appear to have been designed for that. Only Stew will be able to tell when he re-assembles it. And even then it's strange that they went to the trouble of making everything left hand threaded given that there are two tool rests on opposite sides of the wheel.

But whatever, I'm making up a nut and a turned flange, and these parts will get Stew out of trouble. I'll post pictures when it's done.

Graham.

Graham

I really do appreciate your help and your proposed nut and turned flange sounds excellent !

Cheers stew

bunya pine
27th October 2016, 07:49 PM
Not sure if I'm following you. On my other grinders the flange and the nut are one piece.


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Dsel74

The grinder is made for both right and left handers. Ie it turns in both directions with a tool rest on each side.

Interestingly enough, they are different tool rests on each side. The collection of photos of other examples confirm mine are original.

Graham

I suspect it's a left hand thread due to most people being right handed?

Cheers
Stewart

DSEL74
27th October 2016, 07:54 PM
I wonder if the rear rest is in fact there to act as a form of guard perhaps?

Running it in reverse for say lefties will undo the nut.


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bunya pine
27th October 2016, 07:56 PM
I wonder if the rear rest is in fact there to act as a form of guard perhaps?

Running it in reverse for say lefties will undo the nut.


Sent from my iPhone using Tapatalk

The advertisement you posted says it's for left and right hand work......

DSEL74
27th October 2016, 07:59 PM
So it does.


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Oldbikerider
28th October 2016, 10:22 AM
Not sure if I'm following you. On my other grinders the flange and the nut are one piece.

The is a flange on rack side of the emery wheel, only the outside one has spanner flats. There is usually a brass bush that sits inside the wheel to size the hole down to the thread bore.

I'm saying that there is no point in having both threaded parts, the one on the front and the one on the back of the grinding wheel, with left handed threads. A left handed nut would only self tighten on the wheel (and only for one rotation direction) if the threaded part on the opposite side of the wheel was either right handed or fixed against a step in the shaft or by other means.

On Stew's shaft there is a step that the inner flange could lock against, but it doesn't look large enough that it was designed for this. I'm not sure if the way the shaft assembles in the grinder frame allows for the inner flange to even push up against this step. I guess Stew will find out when he puts it back together.

Graham.

DSEL74
28th October 2016, 10:37 AM
I follow you now.

I agree about the inner nut if the grinder is running forward. Would the inner nut tighten if it ran in reverse? So the self tightening action of one nut in either direction provides enough force to keep the wheel in place? Just an idea that popped in my head, might be flawed with more thought lol.

Oldbikerider
30th October 2016, 09:11 PM
Hi Stew,

These parts should work for you. I've made three parts, a thin nut and a flat washer that will go on the outside of the grinding wheel, and a second thicker nut.

The inner flange, the one that came with the grinder, does not run very true. I suspect it's not actually the original, because it doesn't have any flats machined into it and because the thread is not true to the flange face. So I've also made up the thicker nut, which you could use in place of the inner flange if you wanted to. The machined washer has an undercut at it's centre, leaving an outer rim to support the wheel, just as the inner flange does.

I've confident that some combination of these parts will get your grinder up and running. It was fun to make these parts, it's a while since I've needed to do any turning, and this was a nice break from other work. I'll mail the parts back to you tomorrow.

Graham.

398544398542398543398540398541

Oldbikerider
30th October 2016, 09:15 PM
I follow you now.

I agree about the inner nut if the grinder is running forward. Would the inner nut tighten if it ran in reverse? So the self tightening action of one nut in either direction provides enough force to keep the wheel in place? Just an idea that popped in my head, might be flawed with more thought lol.

DSEL74, no I don't think it would. You need opposing threads, or a thread on one side and a hard stop on the other, for the self tightening action to work. And even then it only works for one direction of rotation.

Graham.

bunya pine
30th October 2016, 09:20 PM
Hi Stew,

These parts should work for you. I've made three parts, a thin nut and a flat washer that will go on the outside of the grinding wheel, and a second thicker nut.

The inner flange, the one that came with the grinder, does not run very true. I suspect it's not actually the original, because it doesn't have any flats machined into it and because the thread is not true to the flange face. So I've also made up the thicker nut, which you could use in place of the inner flange if you wanted to. The machined washer has an undercut at it's centre, leaving an outer rim to support the wheel, just as the inner flange does.

I've confident that some combination of these parts will get your grinder up and running. It was fun to make these parts, it's a while since I've needed to do any turning, and this was a nice break from other work. I'll mail the parts back to you tomorrow.

Graham.

398544398542398543398540398541

Graham

That looks beautiful, thank you! I must say it's beyond expectation!

Cheers stew

bunya pine
30th October 2016, 09:21 PM
Graham

Out of interest, what thread was it in the end?

Cheers Stewart

Oldbikerider
30th October 2016, 09:44 PM
It is 1/2", 13 tpi. The shaft thread was too messed up to measure the thread V angle, but I'm guessing it is UNC. If it was 1/2" Whitworth it would have been 12tpi.

Graham.

bunya pine
30th October 2016, 09:46 PM
Thanks

hiroller
30th October 2016, 10:14 PM
Lovely work. Looking forward to assembly.
I have a few Goodell Pratt hand drills that are beautifully made with cut gears that are very smooth.

bunya pine
7th November 2016, 06:12 PM
It is 1/2", 13 tpi. The shaft thread was too messed up to measure the thread V angle, but I'm guessing it is UNC. If it was 1/2" Whitworth it would have been 12tpi.

Graham.

Graham I just received the shaft and nuts! Thanks so much it was a beautiful job!

http://uploads.tapatalk-cdn.com/20161107/ecac139bed67a96929bc3cefe1c333b4.jpg
Now I have to decide if I make it look new again?

http://uploads.tapatalk-cdn.com/20161107/52b50816fa5b73fa1ca300e33229ed8e.jpg

Cheers stew

Oldbikerider
8th November 2016, 01:44 AM
So, does it grind and sharpen tools?

Graham.

bunya pine
8th November 2016, 06:14 AM
So, does it grind and sharpen tools?

Graham.

Sure does!

DSEL74
5th February 2017, 08:59 AM
So did she stay in her work clothes or get a new dress?


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NCArcher
5th February 2017, 09:26 AM
I missed this thread the first time around. What a great little grinder.
You'd need to make sure your tie was tucked into you shirt before sharpening the kitchen knives.
Great job on the turning Graham:2tsup: