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#339819 - 27/11/2010 18:05 Machining question
siberia37
old hand

Registered: 09/01/2002
Posts: 702
Loc: Tacoma,WA
I'm looking at replacing a part on my 4x5" view camera. The part itself is seemingly simple (pic attached). It's basically a 0.5 inch alumnium rod with a 0.25 inch deep slot cut into it. The width of the slot is 0.10" inch at the top of the slot and 0.09" at the bottom.

To those who are familiar with machining- What kind of machining technique would you use to create this part? What kind of tools would be necessary to create it? Is this CNCable?


Attachments
focus_rod.jpg (101 downloads)
Description: Focus Rod Pic



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#339820 - 27/11/2010 18:09 Re: Machining question [Re: siberia37]
tman
carpal tunnel

Registered: 24/12/2001
Posts: 5528
If you can find aluminium or metal rod of the correct diameter then anybody with a decent metalworking shop will be able to grind out that groove for you.

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#339821 - 27/11/2010 18:43 Re: Machining question [Re: tman]
siberia37
old hand

Registered: 09/01/2002
Posts: 702
Loc: Tacoma,WA
I'm sure a machinist could do it. I was just wondering how. Specifically I was thinking of researching if I could do it myself assuming I had the proper tools or if this is out of the question for an amateur to do.

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#339824 - 27/11/2010 19:10 Re: Machining question [Re: siberia37]
tanstaafl.
carpal tunnel

Registered: 08/07/1999
Posts: 5549
Loc: Ajijic, Mexico
Originally Posted By: siberia37
I'm sure a machinist could do it. I was just wondering how. Specifically I was thinking of researching if I could do it myself assuming I had the proper tools or if this is out of the question for an amateur to do.
You are not likely to have the proper tools (if you did, you wouldn't have needed to ask the question! smile ) but with the right tools it would be a simple job.

I bet Mark Lord could make you one out of hardwood that would work!

tanstaafl.
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#339827 - 27/11/2010 20:19 Re: Machining question [Re: siberia37]
Robotic
pooh-bah

Registered: 06/04/2005
Posts: 2026
Loc: Seattle transplant
Slots can be cut on an over-head mill (typical machine) with narrow end mills or with slotting saws.

Examples click me

It's pretty normal stuff for machine shops.

You'll probably want to find someplace to hard-anodize the part, too.
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#339829 - 27/11/2010 22:06 Re: Machining question [Re: Robotic]
mlord
carpal tunnel

Registered: 29/08/2000
Posts: 14493
Loc: Canada
To DIY it, get a suitable aluminium rod, and a 1" thick rectangle of wood, MDF, or plywood, of about two inches longer than the rod.

Cut a dado into the middle area of the wood, the same width/depth as the thickness of the rod. Centre the rod into the dado (slot), and hot-melt glue it in place along the sides of the slot. Glue wooden blocks (plugs) into the ends of the slot to completely secure the rod.

Let the glue(s) harden fully.

Now chuck up a 0.10" thin-kerf carbide-tipped blade in the tablesaw. Flip the assembly face down on the saw, and cut a slot into the rod using repeated passes with increasing kerf depth. When done, break or saw the assembly apart to retrieve the finished rod.

If you don't already have the gear, it may be better to take it to a machine shop.

Cheers

-ml

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#339831 - 27/11/2010 22:34 Re: Machining question [Re: siberia37]
gbeer
carpal tunnel

Registered: 17/12/2000
Posts: 2665
Loc: Manteca, California
Your part seems similar to the part in this pic. The rod that connects the various bits together.



Your part looks like it has a crack. Is that why it needs replacing?

I am curious if the taper from top to bottom of the slot is functional or just from wear? (I suspect it's functional) Does the slot go the full length of the rod?

It's a pretty simple part. It would not need to be CNC'd. With the right saw blade, it's possible to do this on a table saw. Care would need to be taken setting up so fingers are not needed to hold the part. Several passes would be needed cutting down the middle of the slot, then a couple more to create the tapered sides.

Otherwise a machine shop can make one, but it will always be cheaper to buy a replacement part provided one can be sourced.

edit: my choice would be 1)buy replacment 2)machine shop 3)make it my self

Edit2: revised pic


Edited by gbeer (28/11/2010 04:51)
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#339837 - 27/11/2010 23:33 Re: Machining question [Re: gbeer]
siberia37
old hand

Registered: 09/01/2002
Posts: 702
Loc: Tacoma,WA
You are right GBeer that this part comes from a Gowland camera. Unfortunately Peter Gowland passed, so getting parts is not quite so easy anymore- if indeed there are any parts left. My part isn't cracked- it's just a bit deformed inward in spots making focusing difficult.

Thanks for the responses everyone- I will probably end up getting a machinist to do this if I can't source a part. It is encouraging to know I could do it myself if I just had a tablesaw though..

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#339850 - 28/11/2010 02:26 Re: Machining question [Re: siberia37]
mlord
carpal tunnel

Registered: 29/08/2000
Posts: 14493
Loc: Canada
Originally Posted By: siberia37
It is encouraging to know I could do it myself if I just had a tablesaw though..

Plus the $100 special 0.10 thin-kerf blade for it. Standard tablesaw blades (in Canada/USA) cut a 0.125" kerf.

SWMBO and I invested early on in a fully equipped practical workshop, to which we continue to add tools as the need arises.

Best thing we ever did, apart from getting together in the first place. smile

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#339852 - 28/11/2010 02:40 Re: Machining question [Re: mlord]
mlord
carpal tunnel

Registered: 29/08/2000
Posts: 14493
Loc: Canada
(swmbo, having read this post, thinks it's hysterical that tanstaafl suggested MLord would make be able to make sth to do the trick. But, to be honest (should one be honest on a bbs?), you should suggest that the thing is impossible & then I'm sure MLord will build the thing just to prove you wrong wink )

Don't tell him I've stolen his ID to post...

-sjs

(also known as, apparently, though entirely inaccurately as you might guess, as swmbo)

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#339855 - 28/11/2010 04:46 Re: Machining question [Re: siberia37]
gbeer
carpal tunnel

Registered: 17/12/2000
Posts: 2665
Loc: Manteca, California
Originally Posted By: siberia37
You are right GBeer that this part comes from a Gowland camera. Unfortunately Peter Gowland passed, so getting parts is not quite so easy anymore- if indeed there are any parts left. My part isn't cracked- it's just a bit deformed inward in spots making focusing difficult.

Thanks for the responses everyone- I will probably end up getting a machinist to do this if I can't source a part. It is encouraging to know I could do it myself if I just had a tablesaw though..


You might ask about having the part made from alternate materials. 7075-t6 aluminum in much stronger/harder than 6061-t6. Less likely to deform. Or you could opt to have the part made from stainless steel. Be sure to show the machinist the camera and tell him of your need for smooth but tight operation of the focus.

Now that I know the problem is with smooth focus. I'll say definitely, go to a machine shop. Trying to get the necessary tight clearances and finishes just won't happen with a make do operation.
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Glenn

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