# Gears for my oldtimer lathe



## Matthias (Feb 5, 2020)

Hi Guys,

My name is Matthias and I recently discovered this forum site where people share there idees and thoughts.
I'm from Belgium, and I'm in the posession of an old lathe.
It's a Blomqvist 600 or better known as a South Bend 9" (mine is a Swedish model).
The problem is that I don't have the change gears for treading.

My question, is there anybody who have thes gears in reserve or can fabrikate the or have an adres?

My thanks,
And sorry for my bad English


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## Matthias (Feb 5, 2020)

Btw, If possible the metric gears, you know, Europe .


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## catsparadise (Feb 5, 2020)

Hi Matthias,

I suspect it will be very expensive to buy these gears. A check on ebay (uk site) shows a few southbend gears, mainly from the US, and they're asking about £200 plus £100 postage for a set of 10 (sorry, can't find a euro symbol on my keyboard). At £30 per gear that may be a good deal when you consider a cheap gear cutter is around £25 and I'd guess you'd need 3 or 4 of them, plus the steel.

I have the means to cut gears (mill, dividing head) but I don't have many cutters (3 to be precise!). I'm willing to help you out but it will take time, as my time is split between work and machines I'm restoring. If all else fails, PM me and maybe we can sort something out.

Rob


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## kb58 (Feb 5, 2020)

Another option is building an electronic lead screw (ELS). There are a number of people here who have, including myself, for very same reason as you - change gears for my lathe were missing and impossible to find.


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## middle.road (Feb 5, 2020)

3D Printed - possibly. . .









						Are these any good?
					

What do you guys think of these plastic 3D printed metric sets? Will they  stand up?   SOUTH BEND HEAVY 10 METAL LATHE METRIC TRANSPOSING CHANGE GEAR SET 3D Printed  Condition: New   ITEM PRICE:US $64.00 TIME ENDS:Feb-08,01:06 PM SELLER:       fdmprinters(364)Feedback score is 364 for...




					www.hobby-machinist.com


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## brino (Feb 5, 2020)

Hello Matthias, 

Welcome to the site!

Just to add to Dan's (@middle.road 's post above) If you can get access to a 3D-printer you could make them yourself!

The (free for home use) Fusion-360 from AutoDesk has a built-in spur gear generator. You just feed it the specifications and it can generate the .stl file that the 3D-printer needs.

Over here it is possible to get access to a 3D-printer at public libraries and maker-spaces, though most places want you to complete a short intro course first, so you know the basics and don't damage the machine.

I bet if you new the exact spec of all the gears you need, you could find someone to print them for you, for a modest fee.

You could even try the "Can you make something for me" forum here:
https://www.hobby-machinist.com/forums/can-you-make-something-for-me.452/

or the "3D-printer" forum here:
https://www.hobby-machinist.com/forums/3d-printers.224/

-brino


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## Matthias (Feb 6, 2020)

Guys,

thank you all so much, this will help a lot.
I'm looking in to DIY electronic lead screw building projects, but I'm a metal worker and I'm not that edjucated in electronics.
The 3D printing option already crossed my mind, I'm going to calculate the data I need for the gears I need.
I also heve made contact with a vacational school where the students can make 1 gear each .

Meanwhile I going to proceed my quest to find original gears (not only for use but also for the vallue of the machine).

I'l keep you all informed, I love this forum, it's realy edjucational and inspiring to exchanche ideas with people on a distance of 7000km away.
I hope that I can contribute with my ideas in the future.

Greets.


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## pstemari (Feb 6, 2020)

Boston Gear sells on Amazon and makes about every gear a SB 9 could ask for. You'll need to know the pressure angle, module or pitch, and shaft diameter. Pricey, though 

Sent from my Pixel XL using Tapatalk


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## Matthias (Feb 14, 2020)

brino said:


> Hello Matthias,
> 
> Welcome to the site!
> 
> ...


Thx Brino,

I found someone with a very high quality 3D printer.
The only problem is that I need the exact and accurate drawings (if possible digital) to fabricate them.
I have the info like the amount of teeth and the modul (if I'm right) it's 1,5.

should I ask somebody in the other forums that you mentioned?


Thx,


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## brino (Feb 14, 2020)

Matthias said:


> I found someone with a very high quality 3D printer.
> The only problem is that I need the exact and accurate drawings (if possible digital) to fabricate them.
> I have the info like the amount of teeth and the modul (if I'm right) it's 1,5.
> 
> should I ask somebody in the other forums that you mentioned?



Hi Matthias,

If all you need is the *.stl files generated I can do that for you.

I am using the free version of Autodesk Fusion-360 and it has a built-in gear generator.
I will need full gear specifications. 
For metric gears that should be module, tooth count, gear thickness, hub diameter.
There may be a couple other little things like root clearance, etc.

Let me run the tool and I will post back with a screen-shots of the pop-up window.
I should have some time this weekend to generate files.

Perhaps we should take one or two gears thru the entire process (file generation and printing) before we jump into generating all the files?
Unless your access to the 3D-printer works better to have all the files available at one time.
You tell me.

Brian


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## brino (Feb 16, 2020)

Hi @Matthias,

Sorry for the delay.

Within Fusion-360 the Spur Gear generator can be found here:
Tool -> Add-Ins -> Scripts and Add-Ins -> Spur Gear.

For Metric Spur Gears here's the pop-up:



For "English" Spur Gears here's the pop-up:




If you can provide all the required info I can generate the *.stl files.
I think we can just set the "Backlash" and "Root fillet Radius" to recommended vales.

I believe on "true" Southbend lathes that most of the gears were English/Imperial.
Then, for cutting Metric threads on one you need a particular set of "transposing gears" to roughly produce the 1/25.4 ratio.

I think I've heard about it being done with two different transposing gear ratios: 

1) 100/127 
(100/127 = 0.7874015, I think this is the exact solution)

2) 37/47 is another gear combination that produces a set that's "close enough".
(37/47 = 0.7872340)
Also, some lathes have trouble fitting the large diameter 100 and 127 tooth gears, so this reduced ratio (and gear size) really helps.

Do you know for sure what your Blomqvist 600 (Southbend copy) is supposed to use?
It might use "English" gears too.

-brino


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## brino (Feb 16, 2020)

Also, here is a good reference:
https://www.hobby-machinist.com/threads/metric-transposing-gears.27287/

-brino


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## middle.road (Feb 16, 2020)

x3


brino said:


> Hi @Matthias,
> 
> Sorry for the delay.
> 
> ...


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## middle.road (Feb 16, 2020)

brino said:


> Also, here is a good reference:
> https://www.hobby-machinist.com/threads/metric-transposing-gears.27287/
> 
> -brino


You just turned on a light bulb over here with your last two posts and got me to thi_m_king.
My Birmingham 1440 I guess can do metric, but I'm missing the gears to accomplish that. I wonder. . .


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## silverhawk (Mar 7, 2020)

Do we know if the Blomquist 600 used the same gear pitch?


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## NortonDommi (Mar 7, 2020)

Matthias said:


> I'l keep you all informed, I love this forum, it's realy edjucational and inspiring to exchanche ideas with people on a distance of 7000km away.


  I'm 12,535 km from U.S.A.
  Global hobbies.  I bet you find it a lot easier to access materials, parts, tools etc though.


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## martik777 (Mar 8, 2020)

How to cut metric threads w/o conventional transposing gears:




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There are a few South bend gears on https://www.thingiverse.com/search?q=south+bend+gears&dwh=545e6484ae36ed1


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## Jim F (Nov 16, 2020)

The main issue with which gears, is what is the leadscrew pitch? Imperial or metric?


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