- Joined
- Dec 29, 2012
- Messages
- 394
With my new (to me) 14”X30” SLOTTA lathe came as an extra chuck, an 8” 3 jaw ROHM chuck. The chuck had definitely seen better days and, as I had no need for it, I left it aside and forgot all about it.
![Rohm8 a.jpg Rohm8 a.jpg](https://www.hobby-machinist.com/data/attachments/304/304129-4c6f97d9b4929352a8fa0fca2faaa402.jpg)
The biggest issue with it, apart from the abuse by some "hammer lover" owner, was that one of the 3 pinion gears was missing making the chuck a very good paper weight.
The inside of the chuck is in good condition. There is no rust whatsoever but the condition of the existing two pinions is very poor. They are pitted like they have spent their life underwater.
![ssIMG_20201128_005906061.jpg ssIMG_20201128_005906061.jpg](https://www.hobby-machinist.com/data/attachments/304/304130-479a512eb3609070ac094bcaeee364ea.jpg)
Although there is no need to use it at the time, as it requires a back plate that I do not have, and as Covid 19 forced me to spend plenty of time in the shop, I decided to kill some time in trying to make a new pinion for it.
First some measurements to make the blueprints of it.
![ROHM 20 part1.jpg ROHM 20 part1.jpg](https://www.hobby-machinist.com/data/attachments/304/304131-a0424e2bd76df4d790188ff2f6abfed6.jpg)
Apiece of scrap steel in the chuck and the fun begins
![ssIMG_20201129_174048275.jpg ssIMG_20201129_174048275.jpg](https://www.hobby-machinist.com/data/attachments/304/304132-ca947b114e5933536fb96d174e60f529.jpg)
It needed some careful machining though to bring it within dimensions and specs!!!
![ssIMG_20201129_194252553.jpg ssIMG_20201129_194252553.jpg](https://www.hobby-machinist.com/data/attachments/304/304133-ba5cf06f7a50cbef0214e82cc8844179.jpg)
Then I needed to make a cutter for it. I intended to use my mini mill flycutter so I had to make a single point cutter from HSS
To copy the exact profile of the pinion gear, I used hot glue gun, I filled the space in between teeth with hot glue, when solid I removed it. I cut it vertically (using a razor blade) and copied the profile to the HSS.
Minor corrections made with a dremel disk.
![IMG_20201129_194603988.jpg IMG_20201129_194603988.jpg](https://www.hobby-machinist.com/data/attachments/304/304134-9a04f48ccf20c08a4201ea7f8b779ac2.jpg)
Then I put the blanc to the mini mill and using the 4th axis I wrote a simple gcode to make the cut using the fly cutter and the bit I had made.
![ssIMG_20201130_235554160ss.jpg ssIMG_20201130_235554160ss.jpg](https://www.hobby-machinist.com/data/attachments/304/304141-400858783331b5f9f9124cb8d6e4d546.jpg)
It was not an easy job for the mini mill! It struggled to make the cuts although I used very light passes(0.1 mm per pass) and very slow speed. To make the full depth for the 12 teeth took hours.
At the end the pinion gear was ready.
![ssIMG_20201201_231043867.jpg ssIMG_20201201_231043867.jpg](https://www.hobby-machinist.com/data/attachments/304/304138-b585fc5c5e7c9a3e23d0812bc426d1e2.jpg)
Time to test it on the chuck.
Naturally I had to make the securing pin also that was missing as well.
![ssIMG_20201201_231118555.jpg ssIMG_20201201_231118555.jpg](https://www.hobby-machinist.com/data/attachments/304/304139-e3c8dfce3a240e832778dc858c494c14.jpg)
After testing time to cut the unnecessary steel off the back and create the square hole for the chuck key.
I can tell one thing for parting on a lathe: Rigidity is the key to success. With my mini lathe I could never part a piece successfully. I even made a spring parting tool to ease the job (full story here). With the new lathe it was just another job for the machine that was done as it should!
To make the 11mm square hole first I drilled a 10mm hole then I bored it to 11mm.
![ssIMG_20201202_005401336.jpg ssIMG_20201202_005401336.jpg](https://www.hobby-machinist.com/data/attachments/304/304140-14f888a1904230909ebd436a94c203f0.jpg)
Then I took it to the mill where with the help of a 3mm end mill (and some g-code) I made the Square hole.
![ssIMG_20201211_163020062.jpg ssIMG_20201211_163020062.jpg](https://www.hobby-machinist.com/data/attachments/304/304137-38e9dac3b5c349bd96bd5d8af7279e27.jpg)
Sq hole on the spot!
![ssIMG_20201211_165003207.jpg ssIMG_20201211_165003207.jpg](https://www.hobby-machinist.com/data/attachments/304/304142-7c18b83c5a7014b535deeaf58fa83224.jpg)
On the chuck it performs OK.
![ssIMG_20201211_165946455.jpg ssIMG_20201211_165946455.jpg](https://www.hobby-machinist.com/data/attachments/304/304143-d4cfd795e648591f63fced28f983938d.jpg)
And it looks ok also.
![ssIMG_20201211_171755622.jpg ssIMG_20201211_171755622.jpg](https://www.hobby-machinist.com/data/attachments/304/304144-815bace6355261dfb4b35e37f967d1bd.jpg)
Now I have a working chuck that I cannot use because:
a) there is no back plate for it
b) I do not have the set of outside jaws
c) I do not need it for now.
I had a great time in fixing it though!![Big Dancing Banana Smiley Emoticon :dancing banana: :dancing banana:](/styles/default/xenforo/smilies/big-dancing-banana-smiley-emoticon.gif)
Thanks for reading.
Petros
![Rohm8 a.jpg Rohm8 a.jpg](https://www.hobby-machinist.com/data/attachments/304/304129-4c6f97d9b4929352a8fa0fca2faaa402.jpg)
The biggest issue with it, apart from the abuse by some "hammer lover" owner, was that one of the 3 pinion gears was missing making the chuck a very good paper weight.
The inside of the chuck is in good condition. There is no rust whatsoever but the condition of the existing two pinions is very poor. They are pitted like they have spent their life underwater.
![ssIMG_20201128_005906061.jpg ssIMG_20201128_005906061.jpg](https://www.hobby-machinist.com/data/attachments/304/304130-479a512eb3609070ac094bcaeee364ea.jpg)
Although there is no need to use it at the time, as it requires a back plate that I do not have, and as Covid 19 forced me to spend plenty of time in the shop, I decided to kill some time in trying to make a new pinion for it.
First some measurements to make the blueprints of it.
![ROHM 20 part1.jpg ROHM 20 part1.jpg](https://www.hobby-machinist.com/data/attachments/304/304131-a0424e2bd76df4d790188ff2f6abfed6.jpg)
Apiece of scrap steel in the chuck and the fun begins
![ssIMG_20201129_174048275.jpg ssIMG_20201129_174048275.jpg](https://www.hobby-machinist.com/data/attachments/304/304132-ca947b114e5933536fb96d174e60f529.jpg)
It needed some careful machining though to bring it within dimensions and specs!!!
![ssIMG_20201129_194252553.jpg ssIMG_20201129_194252553.jpg](https://www.hobby-machinist.com/data/attachments/304/304133-ba5cf06f7a50cbef0214e82cc8844179.jpg)
Then I needed to make a cutter for it. I intended to use my mini mill flycutter so I had to make a single point cutter from HSS
To copy the exact profile of the pinion gear, I used hot glue gun, I filled the space in between teeth with hot glue, when solid I removed it. I cut it vertically (using a razor blade) and copied the profile to the HSS.
Minor corrections made with a dremel disk.
![IMG_20201129_194603988.jpg IMG_20201129_194603988.jpg](https://www.hobby-machinist.com/data/attachments/304/304134-9a04f48ccf20c08a4201ea7f8b779ac2.jpg)
Then I put the blanc to the mini mill and using the 4th axis I wrote a simple gcode to make the cut using the fly cutter and the bit I had made.
![ssIMG_20201130_235554160ss.jpg ssIMG_20201130_235554160ss.jpg](https://www.hobby-machinist.com/data/attachments/304/304141-400858783331b5f9f9124cb8d6e4d546.jpg)
It was not an easy job for the mini mill! It struggled to make the cuts although I used very light passes(0.1 mm per pass) and very slow speed. To make the full depth for the 12 teeth took hours.
At the end the pinion gear was ready.
![ssIMG_20201201_231043867.jpg ssIMG_20201201_231043867.jpg](https://www.hobby-machinist.com/data/attachments/304/304138-b585fc5c5e7c9a3e23d0812bc426d1e2.jpg)
Time to test it on the chuck.
Naturally I had to make the securing pin also that was missing as well.
![ssIMG_20201201_231118555.jpg ssIMG_20201201_231118555.jpg](https://www.hobby-machinist.com/data/attachments/304/304139-e3c8dfce3a240e832778dc858c494c14.jpg)
After testing time to cut the unnecessary steel off the back and create the square hole for the chuck key.
I can tell one thing for parting on a lathe: Rigidity is the key to success. With my mini lathe I could never part a piece successfully. I even made a spring parting tool to ease the job (full story here). With the new lathe it was just another job for the machine that was done as it should!
To make the 11mm square hole first I drilled a 10mm hole then I bored it to 11mm.
![ssIMG_20201202_005401336.jpg ssIMG_20201202_005401336.jpg](https://www.hobby-machinist.com/data/attachments/304/304140-14f888a1904230909ebd436a94c203f0.jpg)
Then I took it to the mill where with the help of a 3mm end mill (and some g-code) I made the Square hole.
![ssIMG_20201211_163020062.jpg ssIMG_20201211_163020062.jpg](https://www.hobby-machinist.com/data/attachments/304/304137-38e9dac3b5c349bd96bd5d8af7279e27.jpg)
Sq hole on the spot!
![ssIMG_20201211_165003207.jpg ssIMG_20201211_165003207.jpg](https://www.hobby-machinist.com/data/attachments/304/304142-7c18b83c5a7014b535deeaf58fa83224.jpg)
On the chuck it performs OK.
![ssIMG_20201211_165946455.jpg ssIMG_20201211_165946455.jpg](https://www.hobby-machinist.com/data/attachments/304/304143-d4cfd795e648591f63fced28f983938d.jpg)
And it looks ok also.
![ssIMG_20201211_171755622.jpg ssIMG_20201211_171755622.jpg](https://www.hobby-machinist.com/data/attachments/304/304144-815bace6355261dfb4b35e37f967d1bd.jpg)
Now I have a working chuck that I cannot use because:
a) there is no back plate for it
b) I do not have the set of outside jaws
c) I do not need it for now.
I had a great time in fixing it though!
![Big Dancing Banana Smiley Emoticon :dancing banana: :dancing banana:](/styles/default/xenforo/smilies/big-dancing-banana-smiley-emoticon.gif)
Thanks for reading.
Petros
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