Granite Optical Bench Construction

[richard martel]

A few weeks ago I started a thread with a simular title. I removed my contribution to that thread for reasons I believed were valid at the time. After my deletion, Rik removed my posting priviliges. The reasons Rik gave me for his action made very good sense and after a brief email exchange he restored my posting privilege. So once again...

After lurking on this site for some time I decided to build an optical bench. All that I know about this subject I learned on this site. The last time I looked through a microscope was in the sixties.

I am looking for stability for high magnification work and also macro capability. I decided on a vertical column for camera and StackShot mounting for easy acces to the subject. The foundation for this setup is a granite slab that I picked up in Georgia while on vacation. It weighs about 60# and the dimensions are: 3"x12"x20". While not as flat as a granite surface plate it is flat enough for it's intended purpose.





I needed to drill holes into the granite in order to epoxy inserts like this into the holes for mounting the 3x3x27"extruded column.


These are the inserts that will be epoxied into the drilled. They are for a 5/16-18 bolt and require a 1/2" Dia. hole 3/4" deep.



To be continued.

Thanks for looking...

Regards, Richard

[richard martel]

The aluminum column, adjustable slide and fittings were prchased from Alufab in Ohio
http://www.alufab.cc/aluminum_extrusion ... index.htmo...
The diamond core drill D66 5/8 dia. is
http://stores.toolsdirectusa.com/-strse ... Detail.bok from Tools Direct.

After assembling the support feet to the column..







I layed out a paper template of the hole location and transfered the hole centers to the granite plate.



After setting up the drill press to hold the granite slab( the back of the drill press was counterbalanced with weights). The hole center was aligned with a center tool mounted in the drill press chuck and the G.plate was located under its center and the core drill was mounted and a dam formed with plumbers putty.




Depth of hole was set to 3/4 inch and the above procedure was repeated for the remaining holes.

Speed was set to 2300 rpm and the dam filled with water. Drill about 10 seconds and ten seconds cooling with moderate pressure. The drill cuts very fast.



Bob Cubit ... Bob^3. Did something similar constructing his granite plate setup...Maybe he will chime in with his drilling technique.

[AndrewC]

Looks pretty serious - what are you planning to use for lighting / camera ? If you are going to use flash this is way overkill IMHO. Even if you are going to use continuous light it is good to have some mass/inertia but a lot more manageable solution might be to use a smaller base with sorbothane bumpers ?

Regardless of my comments, it looks fun anyway

[ChrisLilley]

This looks as if it will be a really solid, well constructed rig once it is done.

Thanks for posting the blow-by-blow photos and the details of tools and techniques. Always interesting to see how things like this are done.

[Bob^3]

Hi Richard,

I’m very glad you reposted this including the construction details. I sure wish I had seen your methods for drilling the mounting holes in the granite plate prior to drilling mine! I just used a standard carbide masonry drill with a slow water flow to bore-out the holes for my ¼-20 inserts. Your diamond coring drill seems to be providing much cleaner results. And the clay dam to hold the water is a lot less messy(!) than my jury-rigged water flow setup, which "sort of" ran off into a collection pan.

The extruded aluminum Z-axis column looks plenty rigid enough to support the camera and StackShot. And as I stated before, you have the advantage of the “silent shutter” capability with your Canon DSLR.

If you are going to use flash this is way overkill IMHO. Even if you are going to use continuous light it is good to have some mass/inertia but a lot more manageable solution might be to use a smaller base with sorbothane bumpers ?

True, if the plan is to use exclusively short duration flash illumination, this setup might be considered “overkill”. But in my experience it sure is nice to have the option for using various configurations of continuous light illumination. Even using a modeling light for setup and flash for exposure it is difficult to arrange a continuous light source to precisely model the flash source to allow true WYSIWYG results. IMHO for continuous light photography at high magnifications, it can be very easy to underestimate the mass, rigidity and vibration isolation required to achieve "overkill". For a fixed benchtop rig like this, it's better I think to overestimate the requirements in the beginning than be surprised by the poor results and have to fix it later.

I believe Richard is planning on using correctly matched Sorbothane vibration isolators specified for the intended load.

[ChrisR]

Just in the last couple oif years or so, diamond-grit tipped bits have appeared in the merchants in the UK for drilling holes in worktops, tiles and the like. A half inch/13mm one is under $10. They do drill easily and by hand, though a press would always be preferred of course.
I find putty worse than useless for anything at all so don't have any. Blu-tak is fine for the drill moat.

It'll be interesting to see how your project develops, Richard

[Bob^3]

Just in the last couple oif years or so, diamond-grit tipped bits have appeared in the merchants in the UK for drilling holes in worktops, tiles and the like.

That's good to know, Chris. Shows the last time I looked at or purchased a masonry bit. But what will I do with my old carbide set?!

Richard, I'm also curious about how you intend to provide illumination, optical configuration (bellows, lenses, etc.). As you may know even with your solid support, it's good to avoid too much "cantilever" effect by not horizontally extending the camera and rail too far away from the support column. Your sturdy sliding mounting platform is a good start at this.

[rjlittlefield]

Richard, thanks for reposting this material and for adding to it so much more than I had seen before! I'm looking forward to seeing where this goes -- I may need to buy myself a nice hunk of granite one of these days.

--Rik

[Mitch640]

I may need to buy myself a nice hunk of granite one of these days.

No need to be in a hurry, we'll all get our piece of granite eventually.

Speaking of which, a monument place, and most towns will have one, might be a place to find it at a decent price. You could even get it monogrammed, you know, let it do double duty. Who said you can't take it with you? LOL

[NikonUser]

I use a slab of polished granite granite to support my microscope and its camera setup.
It's 27x17x1 1/4" and it was the sink cut-out piece from a kitchen top.
Kitchen top installers that use granite may be a cheap source for such a piece.
My guess is that the cut-put piece has already been paid for by the home owner, their charge is for the whole piece before finishing.
It's a bit like buying lumber, pay for an 8', 2x4 (inches) and you get an 8', 1 1/2 x 3 1/2" piece of wood; plays havoc the very 1st time you design something based on actual 2x4" or 2x6"

[Craig Gerard]

Richard,

I'm trying understand what will go where.

Will the end product look something like this?:
http://www.saphicon.com/motorized-lift.htm

Craig

[Chris S.]

Richard, this is fascinating to follow--thanks for posting, and please keep it up. Very cool stuff to learn.

That said, I'm not sure what you gain from granite versus, say, steel. To my mind, steel is easier to work with, and denser--so you get more mass our of less space, more cheaply, and with characteristics that make it easier to modify later. But there are many ways of getting a job done, and It's great to have a chance to learn from various approaches.

Cheers,

--Chris

[rjlittlefield]

That said, I'm not sure what you gain from granite versus, say, steel.

One advantage of granite, as I understand it, is that it damps any flexing-type vibrations very quickly. You'll never find a piece of granite that "rings like a bell". How much this matters in practice, I have no idea.

--Rik

[AndrewC]

...and denser-...

Tungsten ! I added about 2kgs of mass to one of my wooden bases by adding some Tungsten nails ....

[Mitch640]

You'll never find a piece of granite that "rings like a bell".

That's what I was thinking. I worked in a shipyard for a few years, as a welder. One job I was on was an oil tanker, many hundreds of feet long. Early morning, sitting around on the steel, drinking coffee, you could actually feel someone at the far end of the ship hammering on something. You could see the ripples in your coffee cup. Big hammer, yes, but you could feel it from 400 or 500 feet away. Also, anyone into bird photography knows that metal tripods are the worst kind, transmitting the smallest vibration, while wood or carbon fiber are the best.