Oh, sh!!!! ----Repair??

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ed4copies

ed4copies

Local Chapter Manager
Joined
Mar 25, 2005
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From time to time, I have questions directed to me, particularly about resins.

Today I was reminded of a fairly regular question: How can I repair a clear resin blank?

I have answered--if it is a hairline crack, try to get thin CA to soak into it. Then "clamp" and the resin is likely to "heal" nearly completely--pretty acceptable results.

BUT, if you lose a chunk, what methods have any of you found to replace it (short of re-casting which is "shipping cost prohibitive" in many cases)

I look forward to some good ideas----THANKS!!!

Ed
 
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I've had some big chunks on clear resins and regular assorted acrylics that were repaired by slowly building up multiple layers of thin and medium CA along with dyes if needed until the chunk was built up enough to turn or sand down again.
 
I don't use much clear resin other than those with objects embedded in them. For those, instead of trying to glue the chunk back on, I have just covered the area with med or thick CA and allowed it to cure. Then continue turning. Also works for pinholes in the resin.
 
I have never been impressed with my result using CA---it is an apparent repair. Which leads to TWO questions:
1) How do you apply to make it clear and not obvious?
2) Is there a truly clear epoxy that might work better?

And, yes I am talking about things like circuit board blanks--where something is embedded and the resin is completely clear (probably alumilite-like material).
 
Interesting question - can't wait to see if there is a valid answer. I have not been able to be successful at this at all. The repair is obvious so it never ends up a finished pen.
 
I know all of my own casts have been PR (not alumilite). Most, if not all, of my purchased blanks (clear casts) have also been PR. I don't know if that makes a difference or not.

Make sure to remove all dust and debris. Any white dust will show up. If there are any cracks in the resin, break them off so there is a clean break. The cleaner the break, the clearer the result will be.
 
alphageek said:
Interesting question - can't wait to see if there is a valid answer. I have not been able to be successful at this at all. The repair is obvious so it never ends up a finished pen.
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Dean, you have no idea how many "interesting questions" I get each week. Sometimes, however, I feel there IS a GOOD answer, I just don't have it!

One of the reasons I LOVE IAP---You KNOW Stan has "been there, done that"---so the knowledge is there, I just need to understand why it has not been a successful remedy for MEE:rolleyes::rolleyes::rolleyes::rolleyes:

Now I plan to go to my little turning station here at the office and break some blanks--later today!!

All direction is GREATLY appreciated!!!! (And will help lots of people in addition to me!)


Ed
 
Boy Ed this is a tough one. A crack or a chunk is touph to repair without recasting. The odds of thin CA wicking in unnoticeable with clear PR is slim a chunk even worse. Epoxy and PR sometimes don't play nice together and the epoxy mite not cure proper.

Now I had cracks and chunks the only acceptable repair I did was a recast, not what you wanted I know, But with a crack I would use a dermal tool open the crack up carefully to the base of the blank then recast. PR adheres well to it's self just got to be sure it is CLEAN no wax, no CA no anything.

Sorry couldn't help more.
Bruce
 
Hey Bruce!! I often start my phone answers with, "I know the answer you want to hear, and what I am about to tell you will NOT fill that bill. However, my answer will have one advantage---it IS accurate!"

Guys like you and Stan have been a great asset in gaining knowledge of what will and what "most likely will not" work. I thank ALL of you for your input!!!
 
It looks like you are talking about a technique to repair a chunked $12 blank that can be used by someone without casting gear / supplies. The low budget that implies for the repair really makes a large repair impractical. Additionally, if the patch material doesn't have the same physical / chemical characteristics of the original material (especially refraction index and UV resistance) then the patch will be glaringly obvious. If not immediately, then eventually.

I'm guessing that most of your customers that rip out a chunk of a blank do it when they are knocking off the square corners. How about getting your supplier to round out the blanks they are providing you. Either cast round or turn round. Or you could offer pre-rounded blanks for a premium price.

Just a thought.

Ed
 
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We recommend rounding (on a stationary belt sander, ideally) before turning.

I suspect that some of the blanks may be cracked during the "square turning" phase. But, they actually break apart just before the blank is completely turned.

When or how they break is not really important to the turner in question--he just wants to know if HE can FIX it!!
 
Seems like when I have a chunck fly off, it is on the ends of the blank. When this happens, I will try to cut the defect out which overall shortens the blank. Some kits it works on, but not always. Hope this makes sense.
 
ed4copies said:
We recommend rounding (on a stationary belt sander, ideally) before turning.

I suspect that some of the blanks may be cracked during the "square turning" phase. But, they actually break apart just before the blank is completely turned.

When or how they break is not really important to the turner in question--he just wants to know if HE can FIX it!!
Click to expand...

I know this isn't the fix but maybe another warning to customers.

A source of breaking acrylics is over tightening bushings just one catch can over tighten bushings and you get a squeeze. You want to avoid any thing that can shock the blank. Another big problem area is pressing in parts. If the component is a little too tight or goes in askew CRACK.

Food for thought :biggrin:
.
 
My 2 cents, I've had several expensive circuit board pens get food poisoning and blow huge chunks of clear resin from the ends. If I've been able to find the pices I've CA'd them back on and you don't even see it. If I can't or choose not to (sucked into the dust collector) I've mixed up some 5 minute epoxy and globbed it on. It also is almost impossible if not impossible todetect.
 
We all have the paradigm about PR and that it must be cast and not applied with a brush.
I would replace the piece but open each of the sides of the effected area enough to allow the PR to seep in without too much trouble (make a V channel to allow plenty of exposed area.
Brush a layer of PR onto the tube area place the piece in place and cover the damaged area with PR applied by brush, I would add thicken it to the PR so as to keep it where
you put it.
Let it cure and turn,
Mark
 
I only have "repaired" deep gouges in circuit board blanks. Using thick CA I would apply a thin layer, just as if I were filling a large hole in plaster, giving it several hours to cure. The process took a couple of days but it was off season so I had the time. After building up enough layers to fill the hole I went to turning as normal. I could not discern any visible voids or lines even after polishing. The blank appeared as if nothing had happend.
 
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I had a circuit board blank that chipped on the end of the blank. I build up the area using thick CA ( allowing time for it to cure, don't use accelerator ) and finished turing the blank. When the pen was assembled I was not able to determine where the repair was made.
 
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