Chriske

On 24-4-2017 at 10:39, bobro said:

Here is the link - a download at US$3.95.

https://www.myscienceshop.com/product/digital-download/tmkpdf045

What..!!! Are they still charging for magazines that old...??

Nice work..!!

Not yet Dave, still busy working on this project that absorbs all of my time. It has to be ready for our open door 9/9.
No worries I will post them after our open door weekend, first thing.

Yep, erased all my 57 projects from TV.
I'll host the Printsonian files somewhere else to dowload but later today.
You'll have to do it with the source files, STP instead of STL. There are two reasons why I give you the STP files instead.
1- These Printsonian-STL-files takes almost 1Gb of space. STP is much smaller.
2- STP can be imported in any 3D software, as a bonus you can modify if necessary and convert it to STL yourself afterward.

remind me if I forget...

Files are available of course. There's no reason to keep them hidden from other ATM-friends...

Yep, standard 200x200mm bed will do. At the time I printed this scope I did not have a larger printer.
Now I do, but I wouldn't use it I suppose.

..and thanks for the nice remarks guys...

As Dave_D says don't use RealFilament, had the same problem, couldn't get rid of stringing either.
And what is the trick with this system to adjust the wheels so the carriage runs smoothly without any play at all...?
 

To determine the distance between Primary and secondary cage I always use dummy poles. Thin square wooden poles, or whatever I have  at hand. I fix one set of poles to the secondary cage and the other set of poles to the primary cage. I fix them together with clamps. It's all very basic, don't even think collimating, see to it you can focus on the moon or a bright star, just find the correct distance. If it's not correct just loosen the clamps and slide a bit further. You need clamps, lots of them. If you don't have clamps just screw them together.

While removing clamps PROTECT YOUR MIRROR...!!!

First of all  I don't trust it to work near the edge of the specs, especially with this chinese rubbish. I would buy somewhere else, but I can't determine anymore  whether parts are made in China or not.
but most of all when working near the edge results will become unpredictable, especially visible  in the perimeters. A well tuned hotend, having ran a PID will help improve quality, no doubt about that. It's not the only reason of course, but it helps.
I have no problem printing with 'fat' nozzles, but the layers should always be perfect,  no irregularities are allowed.

dissatisfied ...no not at all,  I used them aal the time on all my printers in the past, but a regular NTC 100k thermistor becomes unstable and unreliable  above 250°C.
Some filament I'm using now (PETG - HT) requires higher temp than 250°C and a  PT100 will go far beyond that temp and is far more accurate to.

On 6/23/2017 at 10:29, Gina said:

Glad you found that E3D Volcano engineering drawing   Yes, I was planning to copy the Volcano but double up on the heaters.  Here's a rough model.  Not sure where to put the little hole for the thermistor.

I'm planning to use a PT100, not a classical thermistor. It needs an additional amplifier board to be connected to the RAMPS.
more info

9 hours ago, Gina said:

Decided to go for 1.75mm filament as an option for this printer and have ordered a couple of Volcano 1.75mm nozzles - 0.8mm and 1.2mm.  I have also decided I'm going to have a go at making a heater block to take two 6mmx20mm 40W 12v heater cartridges, one thermistor and M6 threaded hole for Volcano nozzle.  Like the Volcano heater block I shall use a pair of clamping screws for each heater.  Probably heat conducting grease too.

I think I'll also see if I can arrange to be able to change hotends.

I was planning also to make a volcano for my 1.0 and 1.2.
I would have started here and modify it.
Maybe we can work this out together..?

9 hours ago, Dr_Ju_ju said:

Just check that the cartridge will actually fit the hot-end, I've had some where the diameter was greater than the hole...

reamer...?

9 hours ago, Gina said:

I'm using a 0.8mm nozzle on this machine (0.4mm on the Pilot) and 0.5mm layer height though I think it could probably take a bit more, I'm still experimenting.  I bought an E3D Volcano hotend which came with 5 nozzles of 0.4mm, 0.6mm, 0.8mm, 1.0mm and 1.2mm.  I'm also using E3D Titan extruders on both machines which I've found feed filament a lot better than anything else I've tried including ones I've made myself.  I have tried making my own hotends but had problems.  I have one of those cheapo Chinese mini lathes (for my sins) which I've done my best to improve.  I also have a micro mill - useful for small jobs.

Hotends are pretty quick to change with the E3D Titan extruder - just 4 bolts to take out.  More trouble would be swapping cables over, though the heater and thermistor could be taken out I guess.  I might have another go at making hotends.  Might be advantageous to use a bigger cartridge heater than the standard 40W RepRap type.  I'm finding the "bottleneck" in the extrusion process is the rate at which filament can be melted.  Yes, I know that would be better with smaller filament.

I can't really see how a 2mm nozzle could be used with 1.75mm filament - it would barely touch the sides!!  I suppose it might just work with a relatively small gap between nozzle and print bed.  Once it melted it would "back up" and help the following filament to melt.

While changing hotend I do not swap cables at all. I designed it to be as easy as possible. To swap hotends I only have to remove two screws. All stays in place as a unit. In both XY-carriage and hotend I have two littlt PCB's with contacts. The contactPCB in the XY-carriage has a little bit of play to avoid tension on these PCB's in case of little positioning errors. But as far as I can feel all works very smooth while inserting the hotends in it's carriage.
I also have to remove the partscooling nozzle(2 screws).

9 hours ago, Gina said:

Had a thought - with home made heater block you could have two 40W heater cartridges and connect them in parallel.  The power MOSFETs in the RAMPS are well capable of taking the current.  I've got lots of those 12v 40W cartridge heaters.

I was planning to do that...

The smaller 1.75mm diameter filament and it's higher speed result in a flow that can be controlled far more accurate compared to 3mm filament.
I even use 1.75 mm filament with a 0.7mm nozzle, it gives me smooth prints with no issues(except for the layers itself of course). Layerheight 0.52mm..!
Lucky me (except for the nozzle) I make my hotends myself. I have a lathe and a milling machine.
I integrated a fast exchangeable hotend in my printers. (I do not believe in fast exchangeable nozzles) A few days ago I also bought a 1.0 and a 1.2 mm nozzle... And I read somewhere printing with a 2mm nozzle can be done with a 1.75(!)mm filament..

Gina,

I saw in one of the pictures you use 3mm filament.
you should try printing with 1.75mm  filament. Print quality will improve significantly.

Gina,

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

Nicely done...

Gina,

Will the dome be removed manually or is it a two section dome that will rotate out of the way..?

On 6/19/2017 at 02:36, Chriske said:

 

Here's a list of all electronics involved in this telescope :

1- DSC system. Own design and except for the small gears(mod 0.5) all parts are printed. Connecting with the software(tablet) is done wireless. DSC connection between scope and rocker is done with a timing belt.
2- Green laser pointer(I do not use finderscopes). Push button for that laser is located in the Crayford focuser. Mostly used to initiate the DSC system at the beginning of a session or just to find/point easy objects.
3- Heat control for the green laser.  Laser is kept at 18°C all the time, even in mid-winter.
4- Primary mirror cooling fans. Speed control for these fans is located in one of the Alt-bearings.
5- Boundary layer (Primary mirror) fans. Push button for these fans is located in the Crayford focuser.
6- 2x2 battery compartments. One set is located in the rocker, the other in the scope itself.  I use them in series so I become 14.4 volt for each compartment.
7- Locking system on the altitude bearing. (not yet electronically) Purpose is to allow smooth eyepiece switch without the scope sagging away, losing the object out of the field of view. Problem is the big difference in weight between my smallest end largest eyepiece. When done I slide a counterweight to compensate and release the scope again.
Working on :
8- Dew control for the secondary (that's why all 3 curved spider vanes for the secondary mirror are colored red in the drawing). The 3 metal spider vanes act as leads.
9- Stepper motor for the Crayford focuser. That's why the Crayford is somewhat larger. There is also a micro-switch involved to 'home' the eyepiece.

All electronics are designed and made by Guy, our electronics guru.(mentioned higher up in this thread).

On 6/18/2017 at 07:07, bottletopburly said:

How long to print /complete project 

That's a difficult one to answer...
One of the goals was to hide all electronics and its wiring in the telescope's parts itself so I spent lots of time thinking/drawing how to do that. So during drawing I constantly had to keep in mind and decide whether a part was candidate to include invisible canals to allow all wiring passing through. Assembling the scope and rocker was not easy with that 'wiring-problem'. Many times I had to start all over again because a wire was missing or lead through the wrong parts, ending up at the wrong side of the telescope.
A second important time consuming item was how to make such a large telescope printable on a standard bed. The only solution was to print small parts and bolt or glue them together.

To answer the question : I have no idea, one year, maybe more. Printing itself took me about 60 days(I think...).

All red parts in the drawing are 'hollow' or have 'canals' to allow wiring to pass through or for PCB's or batteries to install.

This is one of the (easy) parts were wiring will pass through.
in this case the wiring is very near the parts inner perimeter.

On 6/18/2017 at 02:41, Mrs Racey said:

What a project. Brilliant. 

I bet that's a bit lighter to heave up the garden than our steel tubed Dob !!

Well I do not know about that, I suppose it is lighter. I did not had a lightweight telescope in mind during designing. I just wanted the telescope to be printable on a standard 200x200mm(8"x8") bed.
The tube's weight is 7.9kg(about 17lb) The rocker's weight is about 13kg(about 28lb), batteries included in both parts. If I would print it again I would consider setting the infill of all parts a bit lower. All parts have now infill 35%.
Both parts have separate power-packs as a lot of electronics is involved.

On 6/18/2017 at 02:39, Racey said:

That's fantastic. 

How's rigidity @Chriske ?

The black (thin wall)l tubes are hardened aluminum, the outer diameter is 35mm(1.4") so the scope itself is very stiff.
The Dob's rocker is made of a (thin walled) steel structure so it is very stiff also. The triangle based structure makes it even stiffer. The green 21mm(0.8") diameter steel tubes are plastic coated.

Except for the aluminum tubes this Dob(own design) is completely printed using a Prusa i2, all is in dutch but the many pictures tell it all. (It took me a few months to draw this thing.)
Enjoy...

The man on the right is Guy, our electronics guru, left is a visitor during our open door.