Broken gear in autofocus

Darkover · 04-18-2019, 11:23 AM

Originally posted by grahame

I always think: there should be a software that if you connect a camera and scan (take a panoramic video) the objectives, you can get the 3-D models automatically.

There are scanner like this. But it is more complicate than you believe.

Your gear is perhaps a standard part. So someone with experience in 3D-software like autocad can draw it in a minute. But a gear should fit very good and perhaps if you print it, it needs to be a little bit smaler or bigger. If you had a 3D-printer in your workshop you would print it three times with different sizes until the tooth fit perfectly.
The next problem. There is a reason why this gear fail so often. I think Pentax calculate something wrong and there is to much pressure in the middle. So perhaps you need the hole a little bit bigger. A very little bit.

Olaf

**grahame** · 04-18-2019, 11:47 AM

I contacted a friend in Japan and asked if he could get the gear from the store. Mailing a camera back and forth cost quite a lot. And I know I can fix it if I have the part.
If he can buy one, I will post here to see in case anyone else need it.

Not a Number · 04-18-2019, 06:21 PM

Any machine shop capable of cutting small gears will cut you one. All you need is the outside diameter, diameter of the opening, thickness and number of teeth. Given those parameters the company in Poland linked above may have them in-stock or will cut them for you.

dcpropilot · 04-18-2019, 11:54 PM

I purchased the brass spur gear from a place in Europe and replaced it myself. Worked fine! I ordered a few to have on hand, and may have some spares.

**felixkh** · 04-19-2019, 12:26 AM

Originally posted by grahame

Thank you for the information. Do you know how much did they charge for the repair?

His repair was 30,000 yen, not inclusive of shipping.

Jyrkira · 02-14-2020, 04:00 PM - **1 Like**

Old thread but I think someone could be interested. AF gear went broke from my FA 31 Limited. It's an old made in Japan version.

So I contacted to Kameraservice Kungsör which is Pentax repair for nordic countries. I asked if they can deliver me a new AF gear assembly. They replied quickly that they can order one from Japan. And they did. Today I received the AF gear assembly and installed it to my 31 Ldt.

AF is smoot again and it works flawlessly.

Here are both AF gear assemblies.

**barondla** · 02-15-2020, 10:04 AM

Would it be possible to put a drop of glue in the gear's fracture and clamp it together to bond?
Thanks,
barondla

Jyrkira · 02-15-2020, 10:55 AM - **1 Like**

Originally posted by barondla

Would it be possible to put a drop of glue in the gear's fracture and clamp it together to bond?
Thanks,
barondla

I think clamping and silver soldering is more durable way to do it. The whole AF gear assembly was not very expensive so I wouldn't bother unless you have all the tools already. Especially when new gear assembly is available.

zzaletel · 12-09-2020, 12:15 AM

Jyrkira - what did the camera service charge you for the replacement gearset?

02-14-2020, 04:00 PM - 1 Like	#21
Jyrkira Senior Member Join Date: May 2009 Location: Finland Posts: 215	Old thread but I think someone could be interested. AF gear went broke from my FA 31 Limited. It's an old made in Japan version. So I contacted to Kameraservice Kungsör which is Pentax repair for nordic countries. I asked if they can deliver me a new AF gear assembly. They replied quickly that they can order one from Japan. And they did. Today I received the AF gear assembly and installed it to my 31 Ldt. AF is smoot again and it works flawlessly. Here are both AF gear assemblies. Last edited by Jyrkira; 02-14-2020 at 04:39 PM.

12-09-2020, 12:15 AM	#24
zzaletel Senior Member Join Date: Dec 2011 Location: Alaska Posts: 144	What the the gearset run? Jyrkira - what did the camera service charge you for the replacement gearset?

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04-18-2019, 11:23 AM	#16
Darkover Forum Member Join Date: Dec 2016 Posts: 68	Originally posted by grahame I always think: there should be a software that if you connect a camera and scan (take a panoramic video) the objectives, you can get the 3-D models automatically. There are scanner like this. But it is more complicate than you believe. Your gear is perhaps a standard part. So someone with experience in 3D-software like autocad can draw it in a minute. But a gear should fit very good and perhaps if you print it, it needs to be a little bit smaler or bigger. If you had a 3D-printer in your workshop you would print it three times with different sizes until the tooth fit perfectly. The next problem. There is a reason why this gear fail so often. I think Pentax calculate something wrong and there is to much pressure in the middle. So perhaps you need the hole a little bit bigger. A very little bit. Olaf

04-18-2019, 11:47 AM	#17
grahame Loyal Site Supporter Join Date: Aug 2011 Photos: Albums Posts: 2,029	I contacted a friend in Japan and asked if he could get the gear from the store. Mailing a camera back and forth cost quite a lot. And I know I can fix it if I have the part. If he can buy one, I will post here to see in case anyone else need it.

04-18-2019, 06:21 PM	#18
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 7,753	Any machine shop capable of cutting small gears will cut you one. All you need is the outside diameter, diameter of the opening, thickness and number of teeth. Given those parameters the company in Poland linked above may have them in-stock or will cut them for you.

04-18-2019, 11:54 PM	#19
dcpropilot Pentaxian Join Date: Mar 2010 Location: Vermont Photos: Gallery \| Albums Posts: 923	I purchased the brass spur gear from a place in Europe and replaced it myself. Worked fine! I ordered a few to have on hand, and may have some spares.

04-19-2019, 12:26 AM	#20
felixkh Site Supporter Join Date: Nov 2008 Location: Singapore Photos: Gallery Posts: 1,184	Originally posted by grahame Thank you for the information. Do you know how much did they charge for the repair? His repair was 30,000 yen, not inclusive of shipping.

02-15-2020, 10:04 AM	#22
barondla Site Supporter Join Date: Sep 2006 Location: midwest, United States Photos: Gallery \| Albums Posts: 4,990	Would it be possible to put a drop of glue in the gear's fracture and clamp it together to bond? Thanks, barondla

02-15-2020, 10:55 AM - 1 Like	#23
Jyrkira Senior Member Join Date: May 2009 Location: Finland Posts: 215	Originally posted by barondla Would it be possible to put a drop of glue in the gear's fracture and clamp it together to bond? Thanks, barondla I think clamping and silver soldering is more durable way to do it. The whole AF gear assembly was not very expensive so I wouldn't bother unless you have all the tools already. Especially when new gear assembly is available.

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