Question: GRS Acrobat lock down

Hi, it has been mentioned in the past that some people "lock down" their GRS Acrobat scope stand.

I understand all of the lever locks ect. on the stand, but still get movement once in a while.Usually because I leaned into the head rest too much some where along the way.

Is there a prefered way to further lock down the stand, other than just taking a wrench to all of the nuts that contol the areas that move?

Any help in this area would be appreciated.

Thanks scott99 :thinking:

Hi Scott99,
I don't know how others do it, but I've found that I do need to lock down the levers with a substantial amount of 'heft'.
Only by hand, but even so, it's a bit more than I would normally consider needed.

I'm just wondering how much pressure you're putting on the head rest, to cause movement.
When I used to use the head rest, I tended to just have it lightly touching my forehead, more as a guide than literally a rest.

Regards,
Jo

Hi back, I normaly just do use the head rest as a lightly touched guide. By that I mean I do not lean on it. What happens over time is a little shift here and there and before I know it I have shifted the Acrobat in enough so as to lose proper centering on my turntable. So I adjust it and go back to work, then bit by bit she shifts just slightly too far and I readjust again (this occurs over a period of days at least).

I was hoping that somebody had put in a pin or block of some sort to eliminate the problem. Like you I also use "a substantial amout of heft" to tighten my locking levers but maybe I am too timid with the whole tightening thing. In the past I have broken more than one type of lever by putting on too much pressure and snapping the things off. I have used my hands over my life to where putting on just enough heft and snapping off a bolt are amounts of pressure that don't lay very far apart.

Thankyou for your reply

scott99

Hi Scott

I just lock everything down with the levers and nuts and don't use a headrest. I found the headrest to be uncomfortable and awkward.

The way to set it up is to take your time setting it up and the final result should be just leaning slightly forward, with no neck or back strain, so that your eyes come to the eyepieces.

Cheers
Andrew

Tighten the nuts with a socket as much as needed- they're not likely to break like a lever might. I don't use the headrest either; it's too itchy

I don't use the headrest either. I lock the articulated arm into position just like you have said. However, I like the scope to move side to side easily so I have more flexibility about what I'm looking at. For that I loosen the 4 nuts near the pole. This allows the entire swing arm to move left and right with minimal touch. Then I use the bridge of my nose to just nudge it when I want it to go slightly left or right. Because I took the headrest off I never lean into it and push it forward - and believe me you won't push it forward with the bridge of you nose. This also allows your eyes not to be so pushed into the lenses. I like to work back a way from them and even take off the black eye caps. This is not how most people work, but it allows me to have more natural head movement and better peripheral vision while I'm engraving as well. Chris D. was the one who showed me about taking off the eye caps. Good luck with your adjustments.

I lock down my levers also and I do like Tira mentioned leave the bolts on the post loose so I can swing the microscope laterally from side to side. I like doing this so I can see what I am engraving actually looks like as the scope with it's magnification can be deceptive. It's real easy to swing it back to center when ready to.
I have always not used the eye cups as they annoy me and is unnecessary. I wear glasses normally but engrave without them as I have perfect up close vision. When using the eyepieces I always felt like when I leave the microscope I would have nice little black rings around my eyes. Of course I never would but it is the workings of a devious mind.
I do have my head rest in place and it I actually us it I would not be very close to the lenses. It's all how you adjust it and I suppose your eyesight too. But I very rarely actually rest on it. I think I just use it for a light touch to align myself then I back off because it is just more comfortable that way.
I do prefer engraving as much as possible with my optivisor because I can see quite well with it and get a better overall picture of what I am doing especially when cutting scrolls and animals. The microscope it great for shading and details as I am at that point working in a smaller area and perameters have already been set to work within.

scott99 said:

Hi back, I normaly just do use the head rest as a lightly touched guide. By that I mean I do not lean on it. What happens over time is a little shift here and there and before I know it I have shifted the Acrobat in enough so as to lose proper centering on my turntable. So I adjust it and go back to work, then bit by bit she shifts just slightly too far and I readjust again (this occurs over a period of days at least). .. In the past I have broken more than one type of lever by putting on too much pressure and snapping the things off...

Click to expand...

Old post but the topic is still relevant. First I don't own an Acrobat stand but am in the process of designing a similiar mechanism customized for my needs. Toward that goal I've spent a fair amount of time studing both Acrobat designs. Concerning locking of the Acrobat's movement, I've noticed the spacers (#10) are grouped in pairs between all bearing surfaces between arms and plates. This seemed a bit curious as depending on spacer material (I speculate a low friction plastic such as nylon or acetal), I didn't immediately see a motivation for the pairing. However the only reason I can envision is to minimize joint friction due to spacer-spacer friction being less than that of spacer-arm and spacer-plate. If so the degree of movement "locking" during use appears limited by design. Furthermore the presence of Belleville spring washers (#49) suggests anticipated usage is where the lever camped joints are snug but not torqued to the point of locking joint movement. Eg, the Belleville washers maintain roughly uniform clampng tension of the joint, despite any contact area irregularities as the joint articulates. Anyway, that's my speculation. So if the spacers are indeed a low friction polymer, substituting a material with greater friction characteristics (a fiber or rigid rubber washer for example) should result in more stiff joint movement without excessive clamping pressure. Also a single spacer should substitute where a pair is used in the original design.

Lastly can anyone enlighten me as to the material used for the arms and connecting plates? I recall being told it was steel however I now suspect the arms are 1x2x1/8" rectangular tube aluminum and the connecting plates are as well 1/8" aluminum. Could an owner of an original Acrobat stand take a magnet to the arms and plates, and confirm either way? Thanks in advance.

uhmgawa said:

Lastly can anyone enlighten me as to the material used for the arms and connecting plates? I recall being told it was steel however I now suspect the arms are 1x2x1/8" rectangular tube aluminum and the connecting plates are as well 1/8" aluminum. Could an owner of an original Acrobat stand take a magnet to the arms and plates, and confirm either way? Thanks in advance.

Click to expand...

The tubes are aluminum, but I believe they may 1/16" tubing... the plates are 1/8" Aluminum, if I recall correctly. I'll measure everything when I'm at the shop on Monday and report back to you.

FANCYGUN said:

When using the eyepieces I always felt like when I leave the microscope I would have nice little black rings around my eyes. Of course I never would but it is the workings of a devious mind.

Click to expand...

using a candle to smoke the eye cups of binoculars is an old prank in the military. once upon a time i had an in-house engraving job and the boss would sneak into my office when i wasn't there to look at whatever i was working on. i'd occasionally call him on it, just a good-humored "So what'd you think about the ____ in my vise?" and he would deny having seen it, but of course i could tell someone had been in my space- tools & things moved around, etc. (the funniest was the half empty cup of cold coffee on my bench. when i handed it back to him, "you left this on my bench.", he stuttered like a boy caught in the bathroom with one of his mom's magazines.)

anyway, i toyed with the idea of smoking the cups on my scope's eyepieces, but figured i wasn't ready to be fired yet...

Mike_Morgan said:

The tubes are aluminum, but I believe they may 1/16" tubing...

Click to expand...

That would surprise me as I wouldn't expect a 1/16" tube wall to provide much of a bearing surface. Actually even with a 1/8" wall a simple steel bolt riding in bare aluminum isn't really ideal from a wear perspective. But given the degree of joint articulation in expected usage the life is probably adequate. It wouldn't take much to open the tube holes to drop-in acetal or bronze bushings if it ever became a concern. Although I would have expected this attention to detail for a stand at this price point.

the plates are 1/8" Aluminum, if I recall correctly.

Click to expand...

Any guess whether the finish on the aluminum is paint/power coat or rather is black anodized? To my eye for the finish appears to be paint vs. an oxide surface.for the versa model.

I'll measure everything when I'm at the shop on Monday and report back to you.

Click to expand...

Many thanks.

I've used black shoe polish... using a candle to smoke rubber eyecups doesn't work out too well...

If you try this on a customer - you better make sure they have a sense of humor first...

Apprentices however, are fair game.


Brian

Abby's brother did a prank on me where he secretly rubbed black gunk into the serrated edges of a quarter and challenged me to roll the quarter's edge up and down and across my face. Of course I accepted the challenge and to everyone's amusement I looked like I had war paint on when I was done. I have a photo of it somewhere.

I keep a couple of 1x2 braces of various lengths handy, to wedge between the bench-top and the Acrobat arm for those moments when the 'scope needs to be very steady. The rest is an exercise in hand-eye coordination.

And I have had enough black eyes over the years, thank you.

uhmgawa said:

That would surprise me as I wouldn't expect a 1/16" tube wall to provide much of a bearing surface. Actually even with a 1/8" wall a simple steel bolt riding in bare aluminum isn't really ideal from a wear perspective. But given the degree of joint articulation in expected usage the life is probably adequate. It wouldn't take much to open the tube holes to drop-in acetal or bronze bushings if it ever became a concern. Although I would have expected this attention to detail for a stand at this price point.


Any guess whether the finish on the aluminum is paint/power coat or rather is black anodized? To my eye for the finish appears to be paint vs. an oxide surface.for the versa model.



Many thanks.

Click to expand...

So, I was wrong... the 1x2" Aluminum is actually 1/8" wall, as you suspected. The plates are also 1/8". The finish is a textured powdercoat.

Thanks for all the tips....Haven't had my microscope for very long yet and seems like I spend more time adjusting it than engraving.

I like the tip about loosening the nuts to be able to move it side to side....I think that would help me tremendously. Can't wait to try it out.