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Tube and Dew Shield Dent Removal Tips

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#1 Kasmos

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Posted 15 March 2017 - 02:05 AM

I thought some of you might be interested in how I removed some dents from a couple of tubes and dew shields.

I also thought this could be a place where others could offer their own experiences and tips.

 

On that note, Here's a link to some dent removal ideas posted by others last June:

https://www.cloudyni...al-suggestions/

 

And here's a somewhat relevant link to a post I made in What did you do to your scope/mount today? on fixing a dew shield that got me motivated to work on some tubes:

https://www.cloudyni...40#entry7675573

 

First up, how I removed five small dents from my Mayflower 806 cutdown.

It was actually the second tube I worked on, but since it's damage is more like what most of you would encounter, I thought it best to start with it.

 

May-806-Tube-Before.jpg

Here's the tube before work. It looked like it was beat with a rock with just about every large chip being the center of a dent. 

 

Most of the work was done with nothing more than a piece of pipe held in a vise.

In my case an old Harley fork tube with a O.D. of 1 9/16".

I also experimented using a plug that I could lightly tap on as a hammer form, but mostly not.

I'll show the plug/hammer form in my next post.

 

Dent-removal-1.jpg

All I did was apply pressure from above with both hands. One held in front and the other behind each dent.

Depending on the size of the ding/dent, sometimes I'd work from the edges of the dent to it's center.

Sometimes the pressure was applied as a jolt of force and or with a combination rocking swiveling motion

of the tube from side to side at each pivot point/dent.

I could be mistaken, but that combo motion seemed to help work out each dent.

It was done a little at a time taking the tube off the pipe and constantly checking my progress.

BTW, If you go a bit too far, you can tap it down while having a plug inside for form.

 

Gauging.jpg

Each dent was marked and a corresponding mark was made on the pipe to gauge it's distance.

After that, I'd just slip the tube to the mark on the pipe (or about where I wanted to start it), angle it a bit, and apply pressure.

This photo was taken a day or two afterwards. I worked on two tubes and may have sometimes had a thin piece of cardboard or more

tape wrapped around the pipe's end to slightly buffer the pressure point. 

 

May-806-Tube-After.jpg

Compare with the top photo. The tube now feels smooth and round to the touch and at most needs a few tiny spots of filler.

 

I had no idea this technique would work, but it really ended up exceeding my expectations.

I've done similar work on car and motorcycle parts and find that you have to (use The Force), sort of feel the metal as you go.

Trust the feel of your fingers as much as your eyes. They can feel things you can't see.


Edited by Kasmos, 15 March 2017 - 03:17 AM.


#2 rolo

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Posted 15 March 2017 - 03:02 AM

Awesome! You can get a job at Fix a Dent and make some serious $$$$!



#3 Kasmos

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Posted 17 March 2017 - 04:38 AM

This is actually the first tube I worked on. It is for a 60mm x 1000mm lens.

It was damaged pretty bad when it was shipped to me. I'd say it looked worse than it does in these photos.

Since it was damaged I figured I didn't really have much to lose by experimenting on it. Also, since I have a 900mm F/L

lens that could use it, I could cut the tube near where the dent was and perhaps work it some more if needed.

Tube-1-Before.jpg

Tube-2Before c.jpg

This was a compound problem. Whatever caused the dent on the top, flattened the bottom end of the tube.

It looks curved but it's really a matter of it being more progressively out of round as it reaches the end of the tube.

Never the less it was going to be challenging.

 

Before I go on, I must say I tried the method mentioned in the article on the Parks 60mm where you stand on a dowel

(pipe in my case), inserted into the tube and strike it with a hammer. Not only did it not work for me, it actually made a

few small outward dents caused by the relatively sharp end of the pipe. I have to say, that really disappointed me.

Tube-3-Before.jpg

This view helps illustrate the flattening.

 

One day without any planning I just got the urge to fix it. Since I was doing it off the cuff, I just looked around the garage

for some round things I might use. The sewer pipe I had used for fixing the a dew shield (link in first post), was slightly too big.

My only other choice was to use a old Harley fork tube and find some thing to enlarge it's diameter.

 

Tubing-PVC.jpg

First I found a piece of 1 1/2" ID PVC but it wouldn't quite fit on to the fork tube. After cutting a slit lengthwise (red arrow), it fit real nice but it wasn't

going to be close enough in diameter to use as a insert plug/hammer form.

Dent-removal-2.jpg

I began to use it as a dent tool as in the previous post but instead used downward leverage as pressure on the tube to work both the dent and the flattened

bottom of the tube. I moved it back and forth along the dent so it would work different parts of the top and the bottom of the tube being careful not to

put too much pressure toward the end of the tube causing it to flare. I was taking it somewhat slow and looked around for another insert before continuing.

 

Next I found a scrap of ABS pipe that was just a little too big to fit the tube. After cutting it length wise with a hacksaw it was still just a tad too big to fit in side the telescope tube.

ABS-Sand.jpg

Clamping a folded piece of sand paper in a vise I was able to slightly enlarge the slit enough to make a tight fit on the other end of the telescope tube.

ABS-Plug.jpg

The great thing about a ABS plug/insert is that you can use WD-40 as a lubricant. It not only helps when you force it into the tube but also when you

knock it out from the other side. To get it in, I tilted the ABS plug at an angle getting one part of it in the tube, then after straightening it, I began

knocking it in with a hammer. Once it was flush I used a large screw driver with alternating blows catching the edges of the ABS insert. Since it is slit,

sometimes the slit ends of the ABS got cocked a bit but it was easy to even it up with the right blows of the screw driver. Forcing it in help bring the tube close

to round again and somewhat pushed out the dent. I pushed it in and out several times but the tube was still not to my liking.  

Pipe-Inserted.jpg

I then wrapped a thin piece of cardboard around the PVC so the ABS insert would have more internal support and drove them both into the tube.

This helped more in bringing the tube back to it's original shape, but when I'd remove the inserts, the tube still wasn't as good as it should be.

Therefore, I went back to using the leverage technique using the PVC pipe finishing up working out the dent as best I could.

 

Another thing I did during all this. I would occasionally use a focuser housing and push it in, then rock it side to side to flex the opening of the tube back to shape.

 

Keep in mind, when working with metal, you have to push things a bit farther than where you want them because they will always flex back some.


Edited by Kasmos, 17 March 2017 - 04:44 AM.


#4 Kasmos

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Posted 17 March 2017 - 04:43 AM

Now the results.

Tube-1-Before.jpg

Tube-1-After.jpg

Tube-2Before.jpg

Tube-2After.jpg

Tube-3-Before.jpg

Tube-3-after.jpg



#5 Ben Bajorek

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Posted 17 March 2017 - 06:10 AM

Nice work.  You could also try and carefully anneal the dented area of the aluminum with a propane torch to soften the metal and make it easier to pull the dent out.  Gently using a smooth sheet metal hammer and dolly/pipe on the annealed dent will shrink the stretched aluminum and make the dent totally disappear.  



#6 TOM KIEHL

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Posted 17 March 2017 - 08:26 AM

Very nice work there Chris . I too have used your methods to remove some stubborn dents . There are some good tips on YouTube buy the PDR ( Paintless Dent Repair ) people . One PDR guy told me the secret is .... work slow from the ends of the dent or crease to the center .  A good florescent light close to the surface helps to see how the glare deflects as you work the dent .

 

I dig these type of " How to " threads waytogo.gif 

 

TK 



#7 Kasmos

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Posted 17 March 2017 - 12:57 PM

Thanks guys.

There was a lot of going back and forth between the techniques since it was sort of a test piece and since it's been a few weeks I forgot to mention a couple of things. When I had both inserts firmly supported in the tube I did some tapping with a plastic tipped hammer starting at a few points at the edges of the dent where it had slightly raised creases and also some along the flattened section to try and flex it round. Also I went back and did some touch up work by using the technique in the first post but with the PVC on the fork tube/pipe since it was a smoother dent. I learned a lot by working on both tubes and had I done them in reverse order (first post was the second one I worked on), the dent probably would have come out even better. 



#8 Kasmos

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Posted 17 March 2017 - 01:18 PM

I don't know how much it would have helped, but later thought of this. It might be helpful to cut a section of ABS pipe something like this for starting it into a misshapen tube 

Insert:Plug Idea.jpg


Edited by Kasmos, 17 March 2017 - 01:19 PM.


#9 xavier

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Posted 17 March 2017 - 05:58 PM

A simple technique I often use is filling the pipe with water and freezing it.  Of course you need to close the the two sides hermetically.  I made stops for all the sizes of Unitron - Polarex scopes.

Ice expands and pushes the dents outwards.  No force. 

the results are perfect.  You only need a large freezer :-)

 

ps: don't forget to inform your partner about the tube.

ps2: don't use the ice in your drinks...



#10 roscoe

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Posted 17 March 2017 - 06:36 PM

These are some really good ideas!!  I have a tube with a sharp crease-dent - looks like someone chopped at it with a hatchet - and I'll give your method a try! 

I normally use a block of wood under a hammer...with a pipe inside the tube.  The block spreads out the hammer blows, which with any sort of a metal hammer, either leaves little dents, or even thin and thus expand the metal, turning a dent into an impossible-to-remove bump

And, I think you said this already, but many small motions is way better than one giant one.....



#11 deSitter

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Posted 17 March 2017 - 06:44 PM

Nice ideas! Amazes me the abuse these things take.

 

-drl



#12 roscoe

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Posted 17 March 2017 - 07:16 PM

When I was a kid, the 'rich kid' down the street got a Unitron for Christmas one year.....probably a 60mm, and I remember, with my icky little Gilbert reflector, being VERY jealous of him and his scope......and by summer, he was using it as a 'baseball bat' to knock rocks out into the back yard!!!!!!  I'm calling that 'extreme abuse!'

Creep!! and of course, he married well and got rich...there is NO justice in this world!



#13 starman876

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Posted 18 March 2017 - 01:36 PM

this is still the easiest way to get dents out of tubes and make out of round tubes round again

 

https://www.walmart....2&wl13=&veh=sem



#14 xavier

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Posted 18 March 2017 - 05:11 PM

this is still the easiest way to get dents out of tubes and make out of round tubes round again

 

https://www.walmart....2&wl13=&veh=sem

Is indeed a professional system if your tube hasn't any baffles or if the tube isn't to long.

My freezing system works well with tubes with baffles. 



#15 starman876

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Posted 18 March 2017 - 07:09 PM

take the baffles out.  fix the tube.  put them nack in. I have plenty of extensions with my socket set


Edited by starman876, 18 March 2017 - 07:10 PM.


#16 TOM KIEHL

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Posted 18 March 2017 - 10:02 PM

A simple technique I often use is filling the pipe with water and freezing it.  Of course you need to close the the two sides hermetically.  I made stops for all the sizes of Unitron - Polarex scopes.

Ice expands and pushes the dents outwards.  No force. 

the results are perfect.  You only need a large freezer :-)

 

ps: don't forget to inform your partner about the tube.

ps2: don't use the ice in your drinks...

Xavier , this technique intrigues me . If you plug both ends and fill the tube with water then freeze . How do you prevent the tube from splitting open once frozen ?   



#17 Kasmos

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Posted 19 March 2017 - 04:47 AM

Now it's time for some Paint Less Dew Shield Dent Repair

 

This is how I fixed the second dew shield I worked on. It's from my newly acquired Cresent 60mm x 800mm refractor.
I would prefer to retain an original finish so I'm trying to just clean up most of the scope without repainting it. At most I'll

be doing some touch ups. That said I wanted to see if I could fix the dew shield without harming the paint.

 

Dew-B.jpg

Here's the subject in question. Very dusty and dirty with a typical flatten edge.

 

01Tape&Pipe.jpg
Once again I am using the same section of 2 7/16" OD scrap pipe I use straightening my first dew shield.
So as not to not harm the inside paint, I wrapped the pipe with a piece of a manilla file folder and the
inside of the dew shield with a 2 or 3 layers of blue painters paint.  Also, any hammering that was done, was
done using this plastic and rubber tipped mallet. (This photo and the one below were taken afterwards).

 

02HandPress.jpg
Again most of the work was done just using hand pressure. Since I was taking the photos I can't show you the
several ways I held it, but sometimes I used my two hands as only my left hand shows in this photo. The exception
being my index fingers were placed a bit higher on top. Other times I used both hands cupped around it in
sort of a choke hold. Another grip that seemed most effective was, one hand cupping on top pushing down,
while a few of my fingers of my other hand were under the pipe pulling from the inside the opposite edge of the
dew shield down. You'd think this might deform the bottom edge, but since I was putting most of the pressure from the top
and held my fingers in such a manner, it did not pull the opposite side out of round.

 

Dew-Dent-removal-1.jpg
While this may not be to scale or the exact angle I always worked at, it gives a general idea of the technique.
Keep in mind it was not done in one brut jolt of force, but rather several times of putting on some pressure, stopping to change
or relieve my grip and trying again. All done in perhaps a period of 30 minutes to an hour.

 

Dew-Points2.jpg

When I first got it started and moving some I could see I had to first tap on these two sharp bends to round them out before continuing.
It was done using the mallet with the pipe acting as an anvil. (This photo was taken before any work was done).

 

Dew-Dent-removal2-.jpg

At one point I had a situation similar to this so I concentrated the pressure where the dip was, similar to taking a dent out of a tube.

 

Dew-Dent-removal3.jpg
It helped but the slight dip didn't completely come out, so once again some tapping using the mallet and anvil technique minimized the dip.

The arrow at left is a bit too far from where I actually tapped.


Edited by Kasmos, 19 March 2017 - 04:53 AM.


#18 Kasmos

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Posted 19 March 2017 - 05:14 AM

...and the results after a little polishing.

Cap-4-After.jpg

Inside and outside paint was not harmed, but If you look real hard there's a faint ghosting of where the dent was.

If you didn't know you probably wouldn't notice it.

 

Cap-Side-S.jpg

I shot this to highlight where the paint is crinkled.

It was not inflicted by my work, but rather from the sharp bend from the original damage.

If you look carefully you can see another smaller spot of it near the other bend point, in the far right highlight.

 

Dew-B&A.jpg

I'll probably smooth the edge and touch it up.

While it's not 100% perfect, being at the bottom it should not show.


Edited by Kasmos, 19 March 2017 - 05:17 AM.


#19 roscoe

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Posted 19 March 2017 - 06:27 AM

this is still the easiest way to get dents out of tubes and make out of round tubes round again

 

https://www.walmart....2&wl13=&veh=sem

One truly amazing thing about opening the world up to third-world manufacturing is that tools like this, which were $100 if you could find them only a few years ago, are now available everywhere for $25!!  The quality/durability isn't quite the same, so if you're a pro, or need the extra accuracy, you still need to flag down the Snap-on truck, but for the rest of us..... 

Not unlike scopes and scope parts.....90% of the quality for 25% of the price!



#20 Ben Bajorek

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Posted 19 March 2017 - 07:12 AM

Rosco have you ever used one those pipe expanders on a telescope tube?  I would think that the spring back of the metal tube while getting expanded to eliminate a dent would require forces that would distort the tube beyond the dented area.  It might be a good tool to roughly push deep dents out and use as a dolly inside a tube while planishing with a hammer.  



#21 starman876

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Posted 19 March 2017 - 07:25 AM

I have used them with great success.  Those pipe expanders are a great tool.   You really do not want to hammer on the tube. The metal gets stretched when you do that and one will never get a truly round tube.  I used to do body work on cars when I was younger and to get the metal truly flat one would have to shrink the metal after it was hammered back into shape to avoid using a ton of bondo.  They were always cheap to buy at the auto parts store.  I remember buying them for $20 30 years ago.



#22 Ben Bajorek

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Posted 19 March 2017 - 08:31 AM

Yes, you can stretch out the metal with a hammer an dolly.  But with the right technique you can shrink the metal and eliminate the dent with a hammer and dolly.  A dent causes the surface to become stretched out in an area.  Eliminating a dent requires the metal to be kneaded together to increased it's thickness in the stretched out area.  Kasmos wrote about working the dent with a hammer from the outside edges to the inside of the dent, this is shrinking.  You are forcing the metal to knead itself together and become thicker.  When I earlier wrote of annealing the aluminum to make it soft it was to facilitate shrinking and reduce the chances of cracking the metal due to work hardening.     



#23 starman876

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Posted 19 March 2017 - 08:37 AM

I like using the proper tool for the job. I have learned the hard way never do anything without the proper tools.   To remove dents you need the proper tools to do it the right way. It saves many hours of having to fix the mistakes you make while trying to do it the hard way.   



#24 Ben Bajorek

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Posted 19 March 2017 - 08:57 AM

Removing dents in sheet metal is an interesting problem.  Simple tools and patience can produce beautiful results.  This is a good forum for information.  

 

http://www.allmetals...fcfc6fdd0&f=13 



#25 deSitter

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Posted 19 March 2017 - 12:56 PM

 

this is still the easiest way to get dents out of tubes and make out of round tubes round again

 

https://www.walmart....2&wl13=&veh=sem

Is indeed a professional system if your tube hasn't any baffles or if the tube isn't to long.

My freezing system works well with tubes with baffles. 

 

I have to say that among ALL ideas, that freezing one is near the top!! As long as you don't burst the tube!

 

-drl




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