Thread: Wickman OPG Optical Grinder.

Originally Posted by Stustoys

Well heating the poly is needed. Without heat everything looks great until you spray some IPA on it and it shows up all the cracking.

Are you sure the IPA isn't causing the cracking? Poly carb is known for stress cracking

Michael

Originally Posted by Michael G

Are you sure the IPA isn't causing the cracking?

"pretty sure"
I did a few halfassed tests but the best proof I have is that the last few I made with a little heat(they are all pretty much the same shape) dont have the problem when sprayed with IPA.

Another option with the bearings is to bin the lot. I guess I'll see how they come up.

Stuart

Originally Posted by Abratool

Stuart
Yes, the ring is there it has a split (like a piston ring) so it looks like it springs out, to the internal dia of the bezel.
The ring is located in the bezel.
I guessed the plastic crystal fits in the groove in the bezel above the ring ?
Maybe I have been wrong. Does it fit below the ring?
If so how do I get the bezel ring assembly off to fit the crystal?
Photo attached of the problem.
regards
Bruce

I tried the link that Anorak Bob gave, & contacted the USA firm for a price on a replacement "Crystal" lens & they came back with a price of US$37 which was a bit more than I anticipated for the Starrett 711.
Thinking of trying to use a 3 point bond of Silicone adhesive, on the OD of the existing "Crystal"... got a feeling that should work.
regards
Bruce

Hi Bruce,
Give it a couple of weeks, I'm sure I'll get it sorted.
Whats the OD of your crystal?

Stuart

Originally Posted by Stustoys

Hi Bruce,
Give it a couple of weeks, I'm sure I'll get it sorted.
Whats the OD of your crystal?

Stuart

Stuart, the ID of the bezel in my Starrett 711 indicator is .905" measured across the diameter of the metal bezel above the spring ring.The OD of the existing Crystal (that falls out) is .885" dia.
The Crystal should be around .915" to .920" OD to be a clip fit into the metal bezel, I would think ?
I suspect the Crystal has "domed" over the years & got smaller in dia.
Thats how it arrived after I purchased it off E Bay in the USA.
regards
Bruce

Well after spending ages cleaning the bearings they appear to be stuffed anyway. Funny circles of different sizes on the bearings??? So I oiled them and put it back together, someones been here before me as there are two different bearing suppliers and sone of the tubes have had a second set of holes for the end caps drilled. Something else is going on as one of the end caps needs to be left loose or it rubs on the end of the shaft.

34E2 10L R&M and 110ACD TH are the bearing numbers 30OD 10mmID.


Hi Bruce,
Sizes are about right. I think I've just about cracked the crystal, but the picture looks shocking. I over heated MkI so it bubbled. Tomorrow maybe.

Stuart

Stu, did the bearings feel rough at all? Those cicles look to me like the balls could have rubbed against some minute particles in the cage. If you cleaned them well, that may not have any effect at all - unless there is a 'burr' on the edges of the circles.... only a microscope would tell. Hang on, you have one or more of those haven't you???

Originally Posted by jhovel

Stu, did the bearings feel rough at all? Those cicles look to me like the balls could have rubbed against some minute particles in the cage. If you cleaned them well, that may not have any effect at all - unless there is a 'burr' on the edges of the circles.... only a microscope would tell. Hang on, you have one or more of those haven't you???

A job for kitty cam maybe....No wait, wrong gender

I may be a little slow on the uptake but what are the rollers for?

Ew

Hi Joe,
Hard to say, they sound pretty shocking loose, but assembled they dont sound "to bad"........but I'm not the best at bearings. The bearings look satin which is a bit of a worry. I found some in the states for $36 each(I need 8) or $6 on ebay......

Hi Ewan,

That bearing picture is from kitty cam(though only on 8X I think).

The wheel and wheel slide are both driven with the same flat belt and are both on a seperate casting that does the vertical wheel slide adjustment from the casting the motor is mounted on......... a picture. that will be easier



Stuart

Well MK8 I think this is pretty much as good as the factory one, part of the machining covers the graduations on the dail but I think thats how they were? Some polishing might improve things, far less noticable when its 1"dia not 7".

Anyone MIG welded cast iron with silcon bronze? I picked up a roll and am thinking about filling up the ends of oil grooves on the work slides. Though given how much work the machine has done to get to this point and how much its going to do going forward I'm not sure its worth it.

Stuart

Originally Posted by Stustoys

Hi Bruce,

We thanks to BT I have a last order to practice on.
Are you sure the bezel hasnt been pushed on to far?
Maybe its missing the ring?(if its an old crystal)
I havent replace any crystals with "new" as yet.

Stuart

Thanks Stuart for posting to me the Crystals for my Starrett 711 Dial Indicator.
The first one I tried to assemble was just a little large in diameter. however the second Crystal was just the perfect size, & it was secured by the spilt wire ring before assembling the bezel back on to the body of the indicator.
It looks & works like a brand new indicator.
I just marvel at the way you have made these Crystals, they are indeed a work of precision.
Thanks again.
regards
Bruce

Hi Bruce,


Glad to help

Originally Posted by Abratool

The first one I tried to assemble was just a little large in diameter.

Hmm, well it fitted this end lol. My first guess is that ploy seems to move slowly for at least while are it is formed*. It was tight when it left here so it wouldnt take much before it wouldnt fit.
The one you've used is as close as I could get to the factory one. It doesnt look so good with a single point light source but in daylight looks fine to me and thats how the factory one is. Tossing the ring out didnt really appeal but that seems to be the way the replacements are done.


On the Wickman side of things I hope to get back to it in the next week or so.

Stuart

*I found this out when I wrecked the first factory crystal in the Mercer off the Wickman. It was stuffed as I over curved it by misstake.......over the next week or so it slowly came back into shape and now you wouldnt know I had even been there unless I showed you.

Archimedes was right!
I needed to move the Wickman back a few feet to make some room. I'd found a use for some of my 36mm bar. 8 or so 6ft lengths and away it went. Manage it mostly by myself with a little help from SWMBO on a couple of occasions. Moved easy as. After a couple of feet it time to lift again so I could move the rollers back the the start. Was a little harder to move sideways as the nuts weren't so happy rolling(which is what they were there for, and ti jack that end up a little)... but just a bit of a shove and it went smoothly enough.

Hope to get back on this job soon(in fact any job would be a start lol)

Stuart

A cunning stunt.