...sorry for the not so humerous typos...

I meant your ... clever design...

I don't know how the Android programmers made the autocorrect pick the worst possible words to use.? Maybe the Android system has Turette syndrome.

(It can't be me can it?)

All the best, and apologies...!

Michael

On Fri, May 21, 2021, 4:20 PM Michael Herman via <mherman346=[email protected]> wrote:

Very nice work.

Please put your steps and photos into a PDF, as the email will become lost over time.? You can then upload your PDF instructions into the group files....and you will be famous forever!? ?Over time,? many people will study your best dead and try it out.

The final step is the most critical.? You just measure your PE from.s star tracking...show the PE is smooth and get the Peak to Peak and RMS PE.? If those are low, you have succeeded well.

Have fun, and thank you again for showing a nice way to upgrade with a DIY spring loaded system, and easy to fabricate parts.? ??

Michael

On Fri, May 21, 2021, 1:58 PM GuitsBoy <guitsboy@...> wrote:

I've had about a half dozen or so nights out imaging with my OnStep converted G11.? My guiding has been pretty good, averaging around .65 to .75 with the old two piece worm blocks and HP brass worms.? After seeing a few posts here and on cloudy nights about DIY spring loaded worm mods, I decided to give it a try myself.?

The raw materials were some 3/4 inch aluminum 90? angle stock, 1/8 thick, some 3D printed attachment points,? a 3D printed drill jig, and some off the shelf hardware.?? Here is the aluminum angle stock marked up for drilling.

I ordered fresh worm blocks so if this mod doesn't quite work out, I can always go back to stock.? I already had extra bearings.? The new blocks were drilled front and top, but only tapped on the front side.? I tapped the top holes to match the front, 10-24 threads.? I also had to file down the corner to get the worm blocks to sit flat in the angle stock.? There is a tiny radius in the extruded aluminum you need to accommodate.

Drilling into a nice mount can be a bit unnerving.? I 3D printed up a jig to make sure I drilled straight, and got the depth right.

A 6-32 tap cuts the threads.?? The rear drill hole does go into the worm block mounting hole, but the bolt does not protrude into it.? No big deal.

One side done, one more to go.

The 3D printed attachment point is in place.

The finished assembly on the DEC side.? The empty outboard hole next to the spring is for a push set screw, if I find it's needed.

And here's the RA side.

Hello little worm, I see you!? You can also see my DIY RA extension I needed to clear the motor brackets.? I'm using 1-1/4 aluminum spacers, and a 3D printed trim ring.?? You can see I did something similar with the DEC as well.

So far, so good.? The pivot point is the bottom worm block bolt closest to the motor.? It's located in place with an m4 x 10mm OD plastic washer.? It is very lightly snugged in place.?? The worm block bolt away from the motor is the sliding side.? It's left loose, only tight enough to keep the worm from walking upward.?

When testing the worm in the OPWB, if I snugged the stock worm blocks into the aluminum angle stock, the worm was difficult to turn.? It could be a burr or defect on both pieces of angle stock, but more likely, the worm blocks / bearings are just off by a fraction of a degree.? I found that torquing the top bolts tightly first, then lightly snugging the front bolts allows the worm to spin freely.

I can just barely get to the motor couplings without taking everything apart, which is nice.? I'm using flexible couplings attached to the belt drive brackets, courtesy of Rockmover on Thingiverse.? I have 16:60 belt reduction, and I'm running the 0.9? stepper motors at 1/16 microsteps, which gives me 0.15 arc-sec or resolution.? Control is handled by OnStep.? Personally, my gut feeling is that attaching the motors directly to the OPWB is unnecessary for the microscopic amount of runout the worm wheels have.? The flexible couplers are more than adequate for taking up any angular error.? I could probably even get away with a rigid coupler and rely on the shaft to flex a tiny bit.? And that's to say nothing of all the plastic. :)

There's clouds in the foreseeable forecast, but I'm hoping there's a break in the weather soon so I can get some testing done.

Any thoughts, comments or criticism are both welcome and appreciated.

-Tony