Question G1003 change gears

[tujungatoes]

New here. Be gentle this is my first post. I recently acquired my first lathe, a Shen Wai sw-900b. From what I’m reading it’s basically the same as the g1003(and numerous others). It came with all the original equipment except the 30t and 32t metric threading gears. I know grizzly hasn’t supported these machines in forever. Does anyone here know of a source for replacements, or specs on the gears for making replacements? Sorry if this has been asked/answered before. I swear I looked.

 

[Mitch Alsup]

Metric has 25.4mm per inch
So big lathes use a 240/254 tooth gear, not so big lathes use a (254/2 =) 127 tooth gear and get essentially perfect pitch matching. Next size down uses 86/91.

My 12×36 lathe uses a 86 tooth gear for english threads and the 91 tooth gear for metric. And has tables of gear box selection for each set of back gearings. The manual downloaded from Grizzly G4003G shows a set of 86/91 teeth gears. 120/127×91/86 = 0.99981 or less than 0.1% "off"

What gears did you receive ?? There may be a way of cutting metric threads by using different gears and chosing the set up on the Norton Gear Box differently. G4003G has 26, 27, 35, 36, 40 installed, 45, 50, 60, 86/91 installed; in the kit which comes with the lathe, so I don't see a 30 and 32 available.

 

[Ken226]

New here. Be gentle this is my first post. I recently acquired my first lathe, a Shen Wai sw-900b. From what I’m reading it’s basically the same as the g1003(and numerous others). It came with all the original equipment except the 30t and 32t metric threading gears. I know grizzly hasn’t supported these machines in forever. Does anyone here know of a source for replacements, or specs on the gears for making replacements? Sorry if this has been asked/answered before. I swear I looked.

Alot of chinese machines in this size range are descendants and modifications of of just a few old designs. As such, there are as many things interchangeable as are not.

Measure the size of the hole / shaft, keyway width, and get the diameter/tooth count of one of your existing gears.

I'll probably be able give you some grizzly lathe model#s that will work with your lathe. Then you can order them from Grizzly.

I have bought and sold a few chinese lathes over the years, and still have gears from all of them. They all fit my current lathe.

I designed and modeled some involute gears in uncommon tooth count sizes so I could cut some weird english and metric thread pitches. They are uploaded to thingiverse. Anyone who's interested can 3d print and use them. I modeled them to work with the Enco, Grizzly, Shop Fox, Birmingham, etc versions of my Birmingham ycl1340gh. Search my username on thingiverse and you'll find them easily.

That model was sold by Shop Fox as the m1019, Grizzly as the G4016, etc. The gears from my old Smithy 12x37 and even a mid 80s Smithy AT300 I one owned fit it. At least, they fit the gearbox input shaft.

The gear/pitch spreadsheet I included with the gear files won't likely match your lathe though. It calculates based on my lathes gearbox ratios.

 

[Ken226]

FYI: the info for the gears I mentioned above seems common to the 13x40 and 14x40 lathes are:

Module 1, diametral pitch 20, bore diameter 19mm, keyway 5mm. Gear width is 10mm. The gears have an integral 10mm spacer, for an overall width of 20mm, pressure angle 20°.

If you measure one of your gears, it'll be easy to figure out if your lathe uses the same gears.

 

[tujungatoes]

Thanks for the replies guys. The gears I received are the inch threading gears. According to the chart, some limited metric threading can be done, with them in different configurations, but for most I’ll need the other two. The inch gears are both 40 tooth and mic out at 52.489mm. I’ve tried plugging them into some formulas to figure out the DP or module...but I got some odd numbers so I’m pretty sure I’m getting lost in the math. I have no clue on pressure angle or how to measure it.... did I mention I’m still super green

It would be great if some of the gears you modeled worked Ken. I have a friend that could print some testers for me.

I’ll attach a pic(not mine) of the setup behind the headstock. it’s very simple.
40t—>127/120–>40

 

[Ken226]

Thanks for the replies guys. The gears I received are the inch threading gears. According to the chart, some limited metric threading can be done, with them in different configurations, but for most I’ll need the other two. The inch gears are both 40 tooth and mic out at 52.489mm. I’ve tried plugging them into some formulas to figure out the DP or module...but I got some odd numbers so I’m pretty sure I’m getting lost in the math. I have no clue on pressure angle or how to measure it.... did I mention I’m still super green

It would be great if some of the gears you modeled worked Ken. I have a friend that could print some testers for me.

I’ll attach a pic(not mine) of the setup behind the headstock. it’s very simple.
40t—>127/120–>40

Mine uses a 40t output and input as well. A 127 and 120 idler set too.

Just those gears alone will let you cut pretty much all common inch, and most metric threads.

Take a pic of your inch and metric pitch chart. I can tell if it has the same gearbox ratios as mine...

Based on your 40t having a diameter of 52.489mm, it is a module 1 with a diametral pitch of 20. Same as mine.

What's the bore diameter?

If your gears have a 19mm bore, my 3d print gears will fit. Also, you can order the 30t from grizzly. The part# is p4016352. Discontinued, but they still have some in stock, though it's 40$

Also, I'm pretty confident that the G0709 uses the same size gears as well. They are cheap enough that it's worth a shot. The pn# for the G0709 32t is p07090203. Also in stock. 13$

Just search the part# on grizzlies website.

 

[tujungatoes]

Mine uses a 40t output and input as well. A 127 and 120 idler set too.

Just those gears alone will let you cut pretty much all common inch, and most metric threads.

Take a pic of your inch and metric pitch chart. I can tell if it has the same gearbox ratios as mine...

Based on your 40t having a diameter of 52.489mm, it is a module 1 with a diametral pitch of 20. Same as mine.

What's the bore diameter?

If your gears have a 19mm bore, my 3d print gears will fit. Also, you can order the 30t from grizzly. The part# is p4016352. Discontinued, but they still have some in stock, though it's 40$

Also, I'm pretty confident that the G0709 uses the same size gears as well. They are cheap enough that it's worth a shot. The pn# for the G0709 32t is p07090203. Also in stock. 13$

Just search the part# on grizzlies website.

Unfortunately, mine has an 18mm hub. I don’t think that’s going to be a deal breaker though. I don’t see why I couldn’t fab a little bushing to make up the difference. I’m definitely going to check out your files on thingiverse too. I should be able to change the hub dimension and get my buddy to print me a couple to test before I throw money at grizzly. Thanks a lot! I’ll report back when I get something going.

 

[tujungatoes]

Oh, and here’s that pic of my threading charts.

 

[Ken226]

Our gearboxes have the same ratios as well.


The spreadsheet file I have on thingiverse will be correct for you lathes gearbox lever positions.

Just fill in the gear tooth count field in the upper right, and the gear lever chart autopopulates all of the pitches for that gear combo.

 

[tujungatoes]

After some Staring at charts and your spreadsheet, it would appear that out gear boxes are only MOSTLY the same. 3, 4, and 5 are just slightly different. Still think I ought to be able to make it work with some little tweaks.