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Gina

DIY Fork Mount for Widefield Imaging Rig

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Gina    9,034

Thanks Julian :)  No, I hadn't forgotten.  I'm expecting to use two Pi3s.

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Gina    9,034

Concentrating on just the casing now.  I'll intersect the semi-cylindrical part with the ring that takes the dome.  I've included the top of the pillar mount for reference.

594a40cd3902f_CasingDiagram01.png.31931a34f2484a7160823a3c316965c5.png

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Gina    9,034

Here's the intersection.  I think I need to increase the diameter of the half cylinder to match the dome support ring.

594a432b62240_CasingDiagram02.png.5608d4019e476dd471221889c6b8705d.png

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Gina    9,034

Some more progress with the intersection.  This shows the curved parts of the casing - the triangular sides are basically flat.  There is end of the half cylinder to do yet though.

594aeb9247b46_CasingDiagram03.png.965c51a36b16845e29b6aa7accec91fb.png

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Gina    9,034

Managed to get "Follow Me" to work on the end.  Not quite right and I'll have another go tomorrow.

594aee1932814_CasingDiagram04.png.8ecb173b3d3556961dd346be4cbd4ec5.png

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Gina    9,034

Improved it a bit.

594ba21b853cc_CasingDiagram05.png.45bbb5a6e4a82f5ef529e3129de8d1aa.png594ba21a9e4fc_CasingDiagram06.png.875204b6f4d8352efd5f4b935ec92f21.png

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Chriske    137

Gina,

what software are you using to make these drawings..?

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Gina    9,034

A bit further with the model just a pity I can't 3d print this in one go :D  Or even two halves.  That with the dome on the top would be aesthetically pleasing IMO :)   All in matching green ABS.

594bab42e33a5_CasingDiagram07.png.25a79264588f6adf3d8583ea8d73acb9.png594bb2823dec3_CasingDiagram09.png.8dc2a09f8836724483f19afa844c863f.png594bb2a66548a_CasingDiagram08.png.a3a2612ba02826fed67fd7abdcee6055.png

Edited by Gina

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Gina    9,034

Just realised - the casing belongs in the dome thread rather than the mount - DOH :hiding:  I'll continue there and keep this thread on topic :D  Fork mount.

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Gina    9,034

Spacers for pillow mount holes - oval holes 16mm x 20mm x 18mm deep with 8mm hole.

59637e2a79f6a_MountBearingSpacers01.png.3ded5f078ef37c2368011f6245e444d8.png

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Gina    9,034

Printing finished.  Two of the four spacers printed in PETG.  They fit the mounting holes perfectly. :)

59639014e8a3a_MountBearingSpacers03.thumb.png.e2210219bd148bb008feae6fc5cc5404.png

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Gina    9,034

Pillow bearings mounted onto aluminium plate using M8 bolts, nuts and washers.

5963b8a565e79_MountBearingSpacers04.thumb.png.54983cb0b38005efa511fbdd2fe17e62.png5963b886096f9_MountBearingSpacers05.thumb.png.4477e5be2c15ed19e9f612e45be3a1d0.png5963b86ff0b83_MountBearings01.thumb.png.6446df45975969d208930c0c0302d260.png5963b85578e33_MountBearings02.thumb.png.d948ff35b356e7fb8a2674e6abc71f9c.png

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Gina    9,034

I've been looking at the elevation required for the mount at this latitude which is about 51°.  Here is a diagram and series of photos as I adjusted the plates to give the right angle - it was higher than I thought :D

5963bbb1d8f5b_MountAngle01.png.e247cf7f1725f115a5eba57b35e7abd5.png

5963bc32b1fb4_MountSupport01.thumb.png.47a28fe05d5b8c50d0372b63590a6b6a.png5963bc1a531d5_MountSupport02.thumb.png.ab11a072e8fd19f57d556b6d3afd1b0a.png5963bc0230093_MountSupport03.thumb.png.25754844179512b38a0c5709b89e1028.png

5963c26554ac8_MountSupport04.thumb.png.6e39c6b9ab8c9d824427cc57fee419de.png

Edited by Gina
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Gina    9,034

This leads me to think again about the method of remotely adjusting the elevation.  I'm tending towards a threaded rod and tapped gear.

Edited by Gina

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Gina    9,034

I have an M8 threaded rod left over from my cannibalisation of the old Velleman kit 3D printer which I think may be suitable.  It is stainless steel and I plan to use a SS nut in a 3D printed spur gear driven by a pinion on a little 28BYJ-48 geared stepper motor.

Edited by Gina

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Gina    9,034

Found the M8 threaded rod and it's more than twice as long as I would need so I consider it unsuitable.  I know I could cut it shorter but I think I would rather not cut it up as it could be more useful for something else.  Probably better to buy a shorter length.

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Gina    9,034

Here are a couple of photos of the mount sitting on the pillar.  I'm using a scrap part as spacer to raise the bearing plate to about the right angle.

596911a23f149_MountonPillar01.thumb.png.999375c587536c9974a110c093328348.png5969117dde196_MountonPillar02.thumb.png.474a1a5e0eade3e117e8d08a823fee44.png

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Gina    9,034

Looked on ebay and Amazon for M8 studding and no joy.  Anything between 200mm (too short) and 500mm (same length as I already have) seem unavailable.  Guess I'll just use what I've got and let the excess hang down below the base part, beside the pillar mount.  May do more to this tomorrow (I have too many projects on the books :D  I just multitask between several at the same time!)

Edited by Gina

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Gina    9,034

I've found an M6 250mm long threaded rod which is long enough (needs about 230mm),  Not stainless steel but zinc plated (galvanised) which is probably adequate - I can coat it with grease and I think M6 should be strong enough.

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Davey-T    9,628

High Gina, I've got a bit of 750mm X 6mm threaded stainless steel  rod I can stick in the post FOC if you want it.

Dave

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Gina    9,034

Thanks for the offer Dave but I think the rod I have will be fine :)

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Gina    9,034

As I've posted in other threads, I'm looking into getting back into astro imaging and trying to sort out where I'd got to since it's been quite a while since I've done anything in this line.  Looks like I shall be needing this mount and its associated dome enclosure for widefield imaging as the EQ8 may be taken over by an Ha solar telescope of similar size and weight to my MN190.

Following on from a suggestion by Ant, I have been using blogs for some of my projects and I think these are more suitable for projects where the input is more from the OP than replies by others.  In other words, where a project is pretty much already designed and not really needing suggestions from other members.  So my plan now is to post ideas and requests for suggestions and advice in the forums and use blogs where the project is either well under way or already completed.

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Gina    9,034

I have found a stainless steel M8 threaded rod of suitable length for the altitude adjustment so that will be helpful when I return to this project.  It is currently on hold as lower priority.

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