# G0709 lathe question?



## Mike8623 (Nov 17, 2018)

Is there a way to get a slower feed rate on my carriage than is listed on the plate? Has anyone done this before and if so how?


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## Ulma Doctor (Nov 17, 2018)

are you using the half nuts or using the feed select lever?
using the longitudinal feed select lever is the slowest/finest feed available without changing gearing

according to the manual the machine is capable of .00168" per revolution as the finest feed


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## mksj (Nov 17, 2018)

Have you checked that your change gears are correct per the chart, I wouldn't want to feed any slower than 0.00168" per revolution which is the lowest setting (FATX1).   Looking at the change gears,  "F" gear setup  yields the lowest feed rate with the gears provided. Any slower feed and you end up rubbing the metal as opposed to cutting it.


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## Mitch Alsup (Nov 17, 2018)

Mike8623 said:


> Is there a way to get a slower feed rate on my carriage than is listed on the plate? Has anyone done this before and if so how?



If you want the feed rate to be slower, change out the back gears from the spindle to the drive.


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## Mike8623 (Nov 17, 2018)

I am wanting to drill a few rifle barrels and would like the lathe to feed slower with the feed lever engaged. Can it be geared down any lower, thus resulting in a slower feed? If it can what gears would you recommend? I would like to go slower than .00168


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## Ulma Doctor (Nov 17, 2018)

now you are talking about making or installing a larger drive gear for the transmission.
for example my shenwai 1236 has a 40 tooth gear drive gear on the transmission
by the example,
you'd need a gear with more than 40 teeth in order to slow the transmission to achieve the reduction you desire
i'm not sure exactly how slow you wish to go, but you could try a 45, or possibly a 50 tooth with the parameters listed above.

without having the actual transmission tooth counts,
computation of the gear split would be challenging as well as speculative on my part


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## mcdanlj (Nov 18, 2018)

Between change gears and the QCGB, there are a lot of potential gear combinations left out of the chart, but the F change gear combination is not merely the slowest on the chart, but also the slowest you can get with the included change gears. I don't know the change gear tooth specification for the G0709 but would be interested to find out.


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## mksj (Nov 18, 2018)

The manual provide the tooth count for the gears, the "F" arrangement" which is the maximum reduction, given the available gears there are no other combinations that will give you a lower feed. Due to the arrangement of gears, even if you could cut new gears, I do not think there is arrangement which you would work because of interference either with other gears or the case cover. So maybe instead of the 32 drive gear you could use something like a  24 tooth which would give a 25% speed reduction. If you know the gear and shaft specifics, you may be able to get a gear for another lathe and/or modify one. I am also not sure that even with such a gear thay you would have enough adjustment range for the other gears, you would need to do some mockup to see if it is even feasible. See below.


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## mcdanlj (Nov 21, 2018)

I have created a google spreadsheet where I'm trying to fill in configurations not on the chart on the front, at least for my 2014-vintage G0709. It's not really useful for you in this case, though, except if you want confirmation that there's no slower combination of gears available through the QCGB.

I haven't validated it *at all* yet; so far it's only math. I'm just working from existing ratios and extending from the chart.


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## BGHansen (Nov 21, 2018)

mcdanlj said:


> I have created a google spreadsheet where I'm trying to fill in configurations not on the chart on the front, at least for my 2014-vintage G0709. It's not really useful for you in this case, though, except if you want confirmation that there's no slower combination of gears available through the QCGB.
> 
> I haven't validated it *at all* yet; so far it's only math. I'm just working from existing ratios and extending from the chart.


Thanks for the spreadsheet!  I've been looking at some oddball threading that between some of the current selections.  Your spreadsheet will help with the gear combos and new gears I'll need to cut to hit the numbers.

Bruce


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## Mike8623 (Nov 21, 2018)

I want to thank all that have replied. So if I replace my 32 gear with a 25 I may get a reduction in feed?

If anyone has done anything like this before on our lathes let me know, what gear to change out to what gear to get a slower feed.

I'm sorry for the late response but I've been busy in my shop cutting out metal and my floor is covered in chips from my mill and lathe. Today is clean up day and then more threading and work on my lathe.


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## mcdanlj (Nov 21, 2018)

BGHansen said:


> Thanks for the spreadsheet!  I've been looking at some oddball threading that between some of the current selections.  Your spreadsheet will help with the gear combos and new gears I'll need to cut to hit the numbers.



Great! I have commenting enabled on the spreadsheet, so please feel free to add comments. I've found and fixed a few typos from my initial data entry, so definitely validate anything before depending on it. I'd love to add change gear specification to the sheet; I'm assuming it's 20⁰ PA since that's pretty much normal for general-purpose modern gears, but can't even guess whether it's metric or imperial...  I don't have gage wires to measure them either.



Mike8623 said:


> I want to thank all that have replied. So if I replace my 32 gear with a 25 I may get a reduction in feed?



I haven't seen the gear specification posted, so if you are buying or cutting new gears yet don't know the correct spec, I'd suggest using a material that won't damage the gears that came with the machine if the spec is off. Acetal or phosphor bronze might be good choices. I have heard of folks 3d-printing gears from ABS successfully, but these teeth are small enough I wouldn't be comfortable doing that myself.


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## mcdanlj (Nov 21, 2018)

mksj said:


> Due to the arrangement of gears, even if you could cut new gears, I do not think there is arrangement which you would work because of interference either with other gears or the case cover.



I looked inside the case cover. There's plenty of room below; the tightest dimension is against the front side of the case. It looks like there is a centimeter or so of radius left against the front of the case cover, but it might require a smaller idler than the 61-tooth idler that is set up by default. So the smaller top driven gear seems a lot simpler if you can find one.


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## Mike8623 (Nov 23, 2018)

mcdanlj said:


> Great! I have commenting enabled on the spreadsheet, so please feel free to add comments. I've found and fixed a few typos from my initial data entry, so definitely validate anything before depending on it. I'd love to add change gear specification to the sheet; I'm assuming it's 20⁰ PA since that's pretty much normal for general-purpose modern gears, but can't even guess whether it's metric or imperial...  I don't have gage wires to measure them either.
> 
> 
> 
> I haven't seen the gear specification posted, so if you are buying or cutting new gears yet don't know the correct spec, I'd suggest using a material that won't damage the gears that came with the machine if the spec is off. Acetal or phosphor bronze might be good choices. I have heard of folks 3d-printing gears from ABS successfully, but these teeth are small enough I wouldn't be comfortable doing that myself.


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## Mike8623 (Nov 23, 2018)

So guys if I find a 24 tooth gear, what pitch would I look for?


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## Winegrower (Nov 23, 2018)

Don’t want to get us off track here, but would appreciate a lecture on the conditions that warrant an actual need for feed rates below 0.001” per revolution.   I haven’t encountered this problem.   Thanks in advance.


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## Mike8623 (Nov 23, 2018)

rifle barrel drilling. All books and data that I've read suggest slower feed rates.

I see Grizzly has a 24t gear for another machine


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