DFA 150 - 450 rotation stopping screw lost

**pichaser** · 12-08-2021, 06:08 PM

Could a 1/4 -20 screw , brass maybe? do the job?
Original screw is best but where to get it .?

Paul the Sunman · 12-08-2021, 09:22 PM

Could you be more specific? Are you talking about the one on the collar? I didn't even know that was removable.

Not a Number · 12-08-2021, 09:44 PM

Screws are most likely metric.

Many online sources including Amazon and eBay. Search for "micro screws" or "micro fasteners". The challenge is knowing what size screw you need. Amazon or eBay you may have to buy in lots. Other sources will sell by the piece if you don't mind paying $5-15 dollars shipping for something that weighs and is the same size as a grain of rice. But I suppose it is better than paying a couple hundred dollars to have it repaired.

**tduell** · 12-08-2021, 10:11 PM

Originally posted by pichaser

Could a 1/4 -20 screw , brass maybe? do the job?
Original screw is best but where to get it .?

I would think the original screw has a special domed or pointed end, to mate with indents in the barrel. If a non-original screw is to be used you may have to modify the end to match.
I just tried to remove mine to check, but it does seem to be non-removable...it certainly gets quite tight as it is unscrewed, so not easy to check the size and thread detail.

Cheers,
Terry

**alfa75ts** · 12-08-2021, 11:03 PM

Originally posted by tduell

it certainly gets quite tight as it is unscrewed

Caution Terry, it looks to be the same as the DA*300 screw. If you force it the 'retaining screw' will damage the thread.

Edit: the thread seems to be an M6 (6mm) coarse.

Paul the Sunman · 12-09-2021, 12:59 AM

My initial surprise that the screw could actually be removed suggests that maybe doing so has caused damage, and a simple screw replacement may not suffice.

**AggieDad** · 12-09-2021, 08:37 AM

Originally posted by alfa75ts

Caution Terry, it looks to be the same as the DA*300 screw. If you force it the 'retaining screw' will damage the thread.
Edit: the thread seems to be an M6 (6mm) coarse.

Per Alfa's nice drawing, it looks as though the retaining screw fell out. You can generally buy a box of mixed sized set-screws on Amazon. With a very quick search I found this set that goes down to M2. If you need smaller (M1 or M1.5) you may need to use a screw with a head.

You can probably replace the main locking screw with a standard M6 caphead screw. You would want to grind the end to a slight point allowing it to set firmly in the detent notch.

**tduell** · 12-09-2021, 02:45 PM

Originally posted by alfa75ts

Caution Terry, it looks to be the same as the DA*300 screw. If you force it the 'retaining screw' will damage the thread.

Thanks for the concern, but no need to worry. I won't be forcing it...it's staying put.

Cheers,
Terry

**pichaser** · 12-09-2021, 03:48 PM

Originally posted by Paul the Sunman

Could you be more specific? Are you talking about the one on the collar? I didn't even know that was removable.

I was very surprised to find no screw to stop the lens from rotating .It was not removable until .

dlhawes · 12-10-2021, 05:28 AM

My local hardware store stocks a gazillion little knobby-things like that and they've got gizmoes setting on the counter for checking thread sizes and such. Just make sure you don't damage the threads in the collar when trying things out. And I agree that knob is almost certainly has metric sized threads.

**pichaser** · 12-10-2021, 08:04 AM

Thanks everyone for all the sincere comments and suggestions . We probably all agree that an original screw would be the best solution with vigilant effort making sure that it doesn't fall out . Of course the ultimate fix would be a trip to a repair facility but I hate to be without the lens for weeks or months . Brass is probably soft enough to be less damaging than steel but it may seize( electrolysis ?) and create a bigger issue . Is there a way to get the original screw? I was stupid enough to lose it and clueless about getting another correct fastener .

Paul the Sunman · 12-10-2021, 02:07 PM

Originally posted by pichaser

Thanks everyone for all the sincere comments and suggestions . We probably all agree that an original screw would be the best solution with vigilant effort making sure that it doesn't fall out . Of course the ultimate fix would be a trip to a repair facility but I hate to be without the lens for weeks or months . Brass is probably soft enough to be less damaging than steel but it may seize( electrolysis ?) and create a bigger issue . Is there a way to get the original screw? I was stupid enough to lose it and clueless about getting another correct fastener .

Maybe you can send the collar for repair, and keep the lens.

**pichaser** · 12-11-2021, 11:43 AM

These photos may help show the situation better . The collar is non detachable in my hands but perhaps someone can . The second photo shows a set screw that is perhaps worn a bit and may need to be replaced . Maybe Santa Claus will intervene ? Thanks to all for caring enough to comment !

12-08-2021, 06:08 PM	#1
pichaser Site Supporter Join Date: Oct 2013 Photos: Gallery Posts: 2,777	DFA 150 - 450 rotation stopping screw lost Could a 1/4 -20 screw , brass maybe? do the job? Original screw is best but where to get it .?

12-08-2021, 11:03 PM	#5
alfa75ts Loyal Site Supporter Join Date: Jun 2009 Location: Melbourne Australia Photos: Albums Posts: 1,356	Originally posted by tduell it certainly gets quite tight as it is unscrewed Caution Terry, it looks to be the same as the DA300 screw. If you force it the 'retaining screw' will damage the thread. Edit: the thread seems to be an M6 (6mm) coarse. Last edited by alfa75ts; 12-08-2021 at 11:12 PM.*

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12-08-2021, 09:22 PM	#2
Paul the Sunman Pentaxian Join Date: Aug 2011 Location: Melbourne Photos: Gallery Posts: 4,843	Could you be more specific? Are you talking about the one on the collar? I didn't even know that was removable.

12-08-2021, 09:44 PM	#3
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Screws are most likely metric. Many online sources including Amazon and eBay. Search for "micro screws" or "micro fasteners". The challenge is knowing what size screw you need. Amazon or eBay you may have to buy in lots. Other sources will sell by the piece if you don't mind paying $5-15 dollars shipping for something that weighs and is the same size as a grain of rice. But I suppose it is better than paying a couple hundred dollars to have it repaired.

12-08-2021, 10:11 PM	#4
tduell Loyal Site Supporter Join Date: May 2015 Location: Melbourne Posts: 1,514	Originally posted by pichaser Could a 1/4 -20 screw , brass maybe? do the job? Original screw is best but where to get it .? I would think the original screw has a special domed or pointed end, to mate with indents in the barrel. If a non-original screw is to be used you may have to modify the end to match. I just tried to remove mine to check, but it does seem to be non-removable...it certainly gets quite tight as it is unscrewed, so not easy to check the size and thread detail. Cheers, Terry

12-09-2021, 12:59 AM	#6
Paul the Sunman Pentaxian Join Date: Aug 2011 Location: Melbourne Photos: Gallery Posts: 4,843	My initial surprise that the screw could actually be removed suggests that maybe doing so has caused damage, and a simple screw replacement may not suffice.

12-09-2021, 08:37 AM	#7
AggieDad Site Supporter Join Date: Jan 2015 Location: Houston, TX Photos: Gallery \| Albums Posts: 1,453	Originally posted by alfa75ts Caution Terry, it looks to be the same as the DA*300 screw. If you force it the 'retaining screw' will damage the thread. Edit: the thread seems to be an M6 (6mm) coarse. Per Alfa's nice drawing, it looks as though the retaining screw fell out. You can generally buy a box of mixed sized set-screws on Amazon. With a very quick search I found this set that goes down to M2. If you need smaller (M1 or M1.5) you may need to use a screw with a head. You can probably replace the main locking screw with a standard M6 caphead screw. You would want to grind the end to a slight point allowing it to set firmly in the detent notch.

12-09-2021, 02:45 PM	#8
tduell Loyal Site Supporter Join Date: May 2015 Location: Melbourne Posts: 1,514	Originally posted by alfa75ts Caution Terry, it looks to be the same as the DA*300 screw. If you force it the 'retaining screw' will damage the thread. Thanks for the concern, but no need to worry. I won't be forcing it...it's staying put. Cheers, Terry

12-09-2021, 03:48 PM	#9
pichaser Site Supporter Join Date: Oct 2013 Photos: Gallery Posts: 2,777 Original Poster	Originally posted by Paul the Sunman Could you be more specific? Are you talking about the one on the collar? I didn't even know that was removable. I was very surprised to find no screw to stop the lens from rotating .It was not removable until .

12-10-2021, 05:28 AM	#10
dlhawes Guest	My local hardware store stocks a gazillion little knobby-things like that and they've got gizmoes setting on the counter for checking thread sizes and such. Just make sure you don't damage the threads in the collar when trying things out. And I agree that knob is almost certainly has metric sized threads.

12-10-2021, 08:04 AM	#11
pichaser Site Supporter Join Date: Oct 2013 Photos: Gallery Posts: 2,777 Original Poster	Thanks everyone for all the sincere comments and suggestions . We probably all agree that an original screw would be the best solution with vigilant effort making sure that it doesn't fall out . Of course the ultimate fix would be a trip to a repair facility but I hate to be without the lens for weeks or months . Brass is probably soft enough to be less damaging than steel but it may seize( electrolysis ?) and create a bigger issue . Is there a way to get the original screw? I was stupid enough to lose it and clueless about getting another correct fastener .

12-10-2021, 02:07 PM	#12
Paul the Sunman Pentaxian Join Date: Aug 2011 Location: Melbourne Photos: Gallery Posts: 4,843	Originally posted by pichaser Thanks everyone for all the sincere comments and suggestions . We probably all agree that an original screw would be the best solution with vigilant effort making sure that it doesn't fall out . Of course the ultimate fix would be a trip to a repair facility but I hate to be without the lens for weeks or months . Brass is probably soft enough to be less damaging than steel but it may seize( electrolysis ?) and create a bigger issue . Is there a way to get the original screw? I was stupid enough to lose it and clueless about getting another correct fastener . Maybe you can send the collar for repair, and keep the lens.