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Need curved steel plate

Dob Reflector
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17 replies to this topic

#1 JJDreese

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Posted 20 July 2021 - 05:25 PM

My two Orion Dobs have a square boilerplate on the inside that allows me to crank down on the viewfinder mount bolts.

My Zhumell doesn't have one and the viewfinder is wiggling all around. I can't tighten it too much or it bends the steel tube.

 

The Zhumell is a 12" and the tube is 14" in diameter.

 

Attached is a photo of the one from an Orion 10" Dob.

 

I suspect it should be 4"x4" steel and 1/16 inch think.   I don't have any metal-working tools. Is there a source to buy one of these?

 

Attached Thumbnails

  • Boilerplate.jpg


#2 Jim Waters

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Posted 20 July 2021 - 06:17 PM

I need one too.


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#3 duck

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Posted 20 July 2021 - 06:22 PM

did you try fender washers?


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#4 Stevegeo

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Posted 20 July 2021 - 06:24 PM

Question, how thick, what size.... inches... I may be able to help.

DM me...  I only need to know a few things.

 

Stevegeo 


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#5 TOMDEY

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Posted 20 July 2021 - 08:19 PM

1/16-inch non-tempered malleable steel is very easy to bend to mild cylindrical shape.    Tom


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#6 KLWalsh

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Posted 20 July 2021 - 08:46 PM

You could contact Hastings Irrigation Tubing. They sell tubing to the ATM market. They might sell you a ‘ring’ of tubing, from which you could cut the section you need. If you don’t already have one, you could get a simple hacksaw and set of blades for like $20.
Or maybe for a reasonable upcharge they’ll cut a piece to the size you need.
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#7 bikerdib

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Posted 20 July 2021 - 08:48 PM

I have a slip roller and could easily roll the shape if I knew the radius, length and width of the piece.  Also, does it need the diagonal on the one end and if so what degree is the angle cut?  I do have a 10" Apertura but that doesn't really tell me what you would need for your 12" Zhumel.  What is the inside diameter of the tube, I'll need to know within an 1/8" or better.  I can make it from either flat steel or aluminum.  If you have any tools, the best thing would be for me to roll the radius in a piece long enough for you to cut to the needed shape and drill the holes.


Edited by bikerdib, 20 July 2021 - 08:50 PM.

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#8 Jon Isaacs

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Posted 20 July 2021 - 09:27 PM

did you try fender washers?

 

Fender washers work..

 

Jon


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#9 Jim Waters

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Posted 20 July 2021 - 09:52 PM

Fender washers work..

 

Jon

How do you get the curvature?


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#10 Jon Isaacs

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Posted 21 July 2021 - 07:36 AM

How do you get the curvature?

 

These are small screws, the washers I am using are relatively small compared to the 1 inch fender washers one uses with 1/4-20 screws.  

 

How heavy is the finder?

 

Jon


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#11 JJDreese

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Posted 23 July 2021 - 12:24 PM

Hi Everybody,

 

Thank you for the offers!  Before I trouble any of you for fabrication (I would pay of course), I am going to try the fender washer route.  I can create a wooden mandrel with proper radius and try to hammer the washers into shape.

I have tools enough to drill the holes and hacksaw some washer parts, but no welding or rolling tools.

 

The 12" Zhumell has a roughly 14" outer tube diameter.  The outer diameter circumference is exactly 44.5 inches.

 

John



#12 Sean Cunneen

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Posted 23 July 2021 - 12:54 PM

You can go to any decent box store or local hardware store and they will have a section of metal rods and bars. you'll need a hacksaw to cut it to the width you'd like and a very long screw to pull the flat piece into the same curve as the tube you have. as mentioned previously the metal will bend and bend very easily. You can also bend it manually around a piece of pipe you may have laying around. in any place that's a lot easier than it looks!
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#13 MitchAlsup

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Posted 23 July 2021 - 04:47 PM

Alternative:: threaded inserts into WOOD !

You can file/sand the wood to an appropriate shape in no time.


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#14 stubeeef

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Posted 23 July 2021 - 07:03 PM

go to Lowes or Home Depot, get a small section of Chimney flue tubing and shape as needed


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#15 Bill Weir

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Posted 23 July 2021 - 09:03 PM

How do you get the curvature?

Pliers? Really though like has been said a small washer is all that’s needed. Worked with changing my focuser in my 6”.

 

Bill


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#16 lphilpot

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Posted 24 July 2021 - 10:48 AM

2" x 1/16" strap aluminum (or steel, if you want that) is generally available at Lowe's, Home Depot, etc. Flex-bend it with the heel of your hand on a hard surface little by little until the arc matches and hacksaw it to length. Drill holes for the bolts and paint.

 

There are more precise ways to do it, but that should work. Or use fender washers as others have indicated. Another alternative might (??) be a piece of stiff plastic such as ABS that will bend to fit when tightened.


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#17 gwlee

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Posted 24 July 2021 - 03:36 PM

I suspect manufacturers wouldn’t bother to fabricate custom steel backing plates if off-the-shelf fender washers worked as well. 


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#18 JJDreese

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Posted 07 August 2021 - 05:01 PM

SOLUTION:

I used 3/4" fender washers.  The 14" diameter of the tube meant I didn't even have to pre-bend the fender washers.  I did use a square of rubber inner-tube between the outside block-mount and the outer tube to prevent any sliding at all.  I painted the washers and locknuts ultra flat black.




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