marcopolo

Chriske, yes i'll need to see how it feels with gloves on. I cant actually raise it without fundamentally changing the force/mechanics/moments on it without maybe a geared raised pinion. A disadvantage of it being ultra low profile I guess. Markse68, the FEA all passed at 200N (that a fairly large force) and the print feels pretty rigid to me. 5mm plate is quite thick. The proof however will be in the pudding. We'll see how it performs once it's built up. Obviously it's getting bolted to a flat wooden OTA so thickness of the base plate is almost irrelevant. I say almost because theoretically the part of the plate that's on the unoccupied side could flex away from the central drawtube area. But like I said the FEA looks pucker!!!

I'm designing and building a high quality crayford focuser. The following points summarise the main goals and design intent as it's really important when I put this design out there in the public domain ANYONE can print out these parts and it will work well. 1. Low cost off the shelf hardware, bearings etc.. 2. High performance having as good as performance as any £150/$200 focuser. 3. Aesthetically looking professional and finished. 4. 30mm drawtube travel and 38mm overall profile height fully racked in from the bottom of the base-plate to the top of the drawtube flange. Ultra low profile. Lowest i've ever seen commercially is 50mm. 5. Can lift at least 1Kg at full extension 90deg to vertical (worst case scenario) 6. Fully 3D printed excepting fixings, bearings and bearing plates. 7. Versions of the base plate to allow different mounting styles/tube shapes etc.... Progress so for is i've done the calculations, force, moments, free body diagrams. CAD completed and completed some FEA. parts printing as of 28/5/20. details below in my blog. I'll do another update during the build/assembly. https://marcosatm.com/2020/05/27/designing-a-high-quality-3d-printed-crayford-focuser/ CRAY_full assembly.avi

It is because the texture allows the slip face on the teflon to work without and suction caused by micro-vaacuums or pocket of air. A bit like a sucker holding low pressure on a piece of glass. Smooth on Smooth can cause "suction"

HI folks, long time no speak. I'm sorry for my absence. If there's one fantastic thing offered up by this lock down it's the chance to reconnect with family but more importantly get back to some proper hardcore telescope building. It's been too long and it's too sad that it should take this to get going again and give us the time to revisit such a beautiful and rewarding hobby. Some of the stuff i've kicked off with again (just because it offers up the biggest quick win over the summer to be ready for autumn) is my 12in F3.3 Newtonian (Dobsonian presently, but will go on a pier eventually). The mirror has been re-coated Orion Hilux so it's all ready for build. I've started blogging my weekly progress with construction detail, recently first light dry run, just to check he focal plane. https://marcosatm.com/2020/05/21/not-quite-first-light/ - First light https://marcosatm.com/2020/05/15/gettin-jiggy-wit-it/ - Some Jigs and fixtures for assembly https://marcosatm.com/2020/05/10/measure-thrice-cut-once/ - Detailing some of the CAD/method Here's a rather spooky fact for you. This mirror was ground and figured in 1984 for Ferranti/ GEC Marconi being used in a laser firing room. Now as it had never seen the light of day in all that time, so first light when I did it this week happened to be Arturus in Bootis as it was very bright in the southern sky, in fact the first star out that night. (I live 55degN so summers are permanent twighlight.). I'm getting to the spooky bit. Arcturus is 36 light years away. You know where i'm going with this. This was complete chance, i'm not making this up. Anyway i'm over at the FB group "Amateur telescope making" posting regularly now. happy building, Marco. www.marcosatm.com