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My New to Me Used G0704

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USMCDOC

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#1
So i bought this G0704 mill the other day, it had a stripped High side gear in it, which i have learned is a common ailment with these mills. So i am considering a belt drive conversion for it, but i want to keep the machine as a manual machine. My concern is that i want to take that intermediate gear out and drive the quill with pully on it where the sensor rotor is attached (with a couple more for good measure) and move the sensor rotor to the top of the pully like SEK_22Hornet did with his..

So is it feasible to do this, and also do the "hockey puck" mod (one of the guys at the shop that i will have to farm this too showed me that he has some left over kevlar to make the bushing out of) for the quill so that the spindle isn't banging on it and also true it up like Russtuff did to his
QuillCleanUp1.png QuillCleanUp2.png QuillCleanUp3.png


and keep this machine in a manual operation? So would the bushing interfere with manual operations? Am i barking up a correct tree with my thinking here?

Either way, i plan on doing the Nachi bearing upgrades for all four of the bearings.

I will also plan on doing the Yuriy's Toys TouchDRO with this machine as well.. (and the lathe as well when i get one)
 

USMCDOC

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#2
Ok.. thought that i would do a before and after pic.. the before is where i just got it up on the bench after driving a total of 12 hours to get this machine.. the after is today.. after putting in a new intermediate gear.

G0704a.jpg G0704b.jpg
You can see how the table looks and matches the color of the bear bottle (which is cold by the way) after removing the vise.
 

coherent

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#3
I'm not quite sure I understand exactly what you are asking. Mine is CNC but that should make no difference. I simply removed the entire high/low selection assembly, put new ac bearings on the spindle and added pulleys. I found both pulleys and the belt on amazon. I couldn't find the shaft bore sizes I needed, but simply ordered some with smaller bores and bored them to size on the lathe and added extra set screws. The existing sensor disc mounted without issue on the top of the pulley using a spacer I printed on the 3d printer. Also printed a simple bracket to remount the sensor so it aligned properly with the disc. Both of the 3d printed parts could have easily been made out of aluminum fairly easily. As a side note the old cover didn't fit after the pulleys were added so I also 3d printed a new cover. I'm happy with the conversion. All in all you'll be much happier with the pulley setup and new bearings. Mine ran very hot and was really noisy. Much cooler and quieter now and my rpm range tops out about 4k making it much more flexible when CNCing aluminum with small end mills. Some folks use a double pulley setup on both the spindle and the motor to allow high/low rpm options. Keep in mind that the method I used removes use of the quill of course, but on a CNC converted machine that's not an issue. On a manual machine it would be. If what you are trying to do is mount the pulley to the primary shaft and retain use of the quill, that's not a problem either. There are a couple of companies that make a conversion kit that retains use of the quill. Do a search and look at their assembly instructions and it will be fairly clear how this is done. Benchtop Precision sells just the new bearing carrier by itself that allows you to keep use of the quill. That part in itself with the female splines would be pretty involved to machine in a home shop.
 
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USMCDOC

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#4
I'm not quite sure I understand exactly what you are asking. Mine is CNC but that should make no difference. I simply removed the entire high/low selection assembly, put new ac bearings on the spindle and added pulleys. I found both pulleys and the belt on amazon. I couldn't find the shaft bore sizes I needed, but simply ordered some with smaller bores and bored them to size on the lathe and added extra set screws. The existing sensor disc mounted without issue on the top of the pulley using a spacer I printed on the 3d printer. Also printed a simple bracket to remount the sensor so it aligned properly with the disc. Both of the 3d printed parts could have easily been made out of aluminum fairly easily. As a side note the old cover didn't fit after the pulleys were added so I also 3d printed a new cover. I'm happy with the conversion. All in all you'll be much happier with the pulley setup and new bearings. Mine ran very hot and was really noisy. Much cooler and quieter now and my rpm range tops out about 4k making it much more flexible when CNCing aluminum with small end mills. Some folks use a double pulley setup on both the spindle and the motor to allow high/low rpm options. Keep in mind that the method I used removes use of the quill of course, but on a CNC converted machine that's not an issue. On a manual machine it would be. If what you are trying to do is mount the pulley to the primary shaft and retain use of the quill, that's not a problem either. There are a couple of companies that make a conversion kit that retains use of the quill. Do a search and look at their assembly instructions and it will be fairly clear how this is done. Benchtop Precision sells just the new bearing carrier by itself that allows you to keep use of the quill. That part in itself with the female splines would be pretty involved to machine in a home shop.
I am going with the following bearings.. From my research to this point, these provide less runout then the AC bearings that have been listed in the past for this machine.. here are the bearings that i will be buying for this machine

Nachi 6007ZZE
Nachi 6209ZZE
Nachi 32005
Nachi 32007

As to what i am asking was about the cleaning up of the gear hub as shown in the above pics, if it would work with the machine being used in manual.. vs CNC.. i don't plan on going the CNC route.. but from studying the exploded views on the Grizzly site.. i have determined that yes, that the hub can be cleaned up and still use the machine in manual. I will just have to mount the pully for the conversion over to belt drive to the top of the hub as did @SEK_22Hornet did on his machine.

My only concern now is.. with the bushing in the quill to stop the "rattle" of the spindle slapping the quill as they are prone to do in this machine.. will have to be a bit deeper in the quill, to give full support to the spindle as it is manually moved up and down since this isn't going to be a CNC machine. It will have to be at least the length of the depth in the quill so that the spindle is fully supported all the way to the max travel of the spindle. It is either that, or find a way to fasten the "bushing" to the spindle so that it will move with it as the it goes down and up..


Does this make sense to you?
 

USMCDOC

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#5
There are a couple of companies that make a conversion kit that retains use of the quill. Do a search and look at their assembly instructions and it will be fairly clear how this is done. Benchtop Precision sells just the new bearing carrier by itself that allows you to keep use of the quill. That part in itself with the female splines would be pretty involved to machine in a home shop.
Benchtop Precision is the only person that i have found on the interweb that makes a belt drive conversion kit for this machine. That or my "google fu" isn't all that great!
 

coherent

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#6
OK, understand what you mean now. The top end of the spindle shaft is not supported by the bearings so you are correct, it wobbles by hand when you move it side to side. I printed a 3d spacer that slides onto the splines. Hoss mentions it and shows a photo of one on the CNCZone forum. He called it an "antivibration adapter". See post #4 here http://www.cnczone.com/forums/benchtop-machines/200192-g0704-spindle-vibration.html

It does make a difference, but I don't use the quill so it's a cheap easy fix. I don't feel a plastic spacer is the very best solution. Also not sure if its even practical for quill use. I would think that the replacement shaft sold by benchtop precision would be the better fix, but since I have never seen one/mounted and tested it myself, am only assuming. If you come up with a better alternative I would be interested in seeing it. I'm sure some type of additional bearing/mount could be designed to fix the issue, but I didn't take it any further than the 3d printed adapter.
There is a guy in NZ who has a couple of belt drive kits listed http://www.smt.co.nz/belt-drives. There used to be at least one other, but it didn't come up on a quick search. Occasionally you see something posted on ebay.
 

USMCDOC

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#7
OK, understand what you mean now. The top end of the spindle shaft is not supported by the bearings so you are correct, it wobbles by hand when you move it side to side. I printed a 3d spacer that slides onto the splines. Hoss mentions it and shows a photo of one on the CNCZone forum. He called it an "antivibration adapter". See post #4 here http://www.cnczone.com/forums/benchtop-machines/200192-g0704-spindle-vibration.html

It does make a difference, but I don't use the quill so it's a cheap easy fix. I don't feel a plastic spacer is the very best solution. Also not sure if its even practical for quill use. I would think that the replacement shaft sold by benchtop precision would be the better fix, but since I have never seen one/mounted and tested it myself, am only assuming. If you come up with a better alternative I would be interested in seeing it. I'm sure some type of additional bearing/mount could be designed to fix the issue, but I didn't take it any further than the 3d printed adapter.
There is a guy in NZ who has a couple of belt drive kits listed http://www.smt.co.nz/belt-drives. There used to be at least one other, but it didn't come up on a quick search. Occasionally you see something posted on ebay.
Also with the Nachi 32005 and 32007 bearings.. you won't have to worry about having to make a spacer as when you would have to with the AC bearings..
 

USMCDOC

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#8
20170605_185723.jpg 20170605_185734.jpg

Just picked up some Accuremote scales from Amazon.. i have them adjusted now that on one full rev of the dial i get 0.100 of movement! Sadly, you lose some of that Y travel.. But i seen were Rus (Russtuff on youtube) had come up with a way to get some of that back. But i am not sure if i want to go there or not..
 

USMCDOC

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#9
Ok.. made a bushing for the quill.. i put it down under the spring.. it did reduce the spindle travel to 1.005 inches. But i think that will be ok.. i don't think that i will be needing to do any deep drilling it.. and if i have too i will do it in steps i guess...
20170606_172623.jpg
 

USMCDOC

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#11
Well to be honest.. i don't think that "quill" travel is going to be an issue really.. the head still goes up and down
 

wrmiller

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#12
On mine I only used the quill for occasional drilling, and to get my Z reference set. Used a drill press for deeper stuff. :)
 
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