Making a Vixen Style Dovetail bar for 3d printing and use with a telescope mount


#1

First, please forgive my sad newbie knowledge with sketchup. I’m pretty comfortable with most graphic design software (photoshop, cc suite etc…), but I’ve literally only just started tinkering with Sketchup. I’m am just starting out with 3d printing, and this is my first design. I know the wisdom is usually you need to walk before you can run, but this is something I actually need, and there is no pre existing design that I’ve found. This is basically a rectangle shaped bar, that is attached to a telescope, and the bar is then attached to the telescope mount. (MEADE LXD75).

I’ve managed to setup a “base” shape/layer for the item in sketchup, and ensure the 3 axis dimensions are accurate to final sizes (11" long, 1.7" wide, 0.5" tall). As great as it would be if the design was super simplistic…it isn’t (see images). It’s not horribly complex, but it does require specific modifications along pre existing flat faces. For example, the side length face of the rectangle that is currently flat, needs a section in the middle to be “detached” from the rest of the face, and angled inwards. I think it’s easier to post pictures of where I am at, and what the finished product should be, and let you all offer input. See below

The final product should look like the images listed under GP/SX Series Male Dovetail Plate at this page: http://www.company7.com/vixen/mounts/mounthd.html


#2

Can you share your SKP file to this point?

Check your private messages.


#3


#4

Correct, that screenshot is the bar in question (didn’t know if I should be posting too many pics for starter account). Here’s a shot of the mount “saddle” where the dovetail bar will be connecting. The two sections sticking out are angled inwards in the saddle


#5

And I will upload that file when I get home shortly


#6

see .skp for my go at it…without more specific dimensions it will be all guesswork…click on scene tabs to follow progression.

Charlie

AmAd3809_07_22_2018.skp (1.0 MB)


#7

WOW! Charlie that’s amazing! I wasn’t expecting a full hand holding tutorial, but I certainly wasn’t expecting anyone to full out model it for me! Thank you so much. What I have been told, is that the sections of the bar that are angled inwards are set at 15 degrees. So what I was struggling with initially, was editing the side faces of the initially flat rectangle sides. As I can see with what you did, You have the center section of the rectangle side inset. That was what I was struggling with. Trying to figure out how to take a section of a pre-existing face, and edit/move it as a separate entity without affecting the face on either side of the center section. May I ask with your approach to this (or if anyone else reading this were to approach this), would you start with a full rectangle shape as you can see was my approach on the picture I posted? I guess I was looking at it more as a carver or sculpter would…start with the full shape and cut away at it to leave what you want. Or was the approach to draw out the sections and slopes as different pieces and join them?

One last question: As you can read in the specs and see, this will be threading bolts, probably 1/4-20 size. So how is that approached? How are threads done in 3d printing? Do you actually model the threads into the hole? Or just have a hole and thread/drill into it with the target size to form them? I’m sure you all can infer that this is intended to be quite sturdy, so I obviously won’t be using flexible material, and going with the hardest one available. As always, grateful for any input and thoughts from all


#8

Wow…again lol! I think some of those questions above were answered already, because I wrote it just looking at the finished product screenshot on that file before actually opening it.


#9

Sorry for the delay in getting back to you. I’ve been out all day.

Looks like Charlie has you mostly sorted. As for your question about threaded holes, you can model machine threads but you would be better off drilling and tapping the holes after the part is made. Getting the threads to print exactly right is problematic and you probably don’t want to count on them in this application. If the threads need to be very durable, you might consider threaded inserts instead.


#10

You are quite welcome…I don’t know what angle the dovetail is currently as i just measured back I think 1/8” and drew lines at intersecting guide lines.
To set that angle to 15 degrees you could just use the protractor tool and do the same procedure I illustrated.

Fire away with any other questions as they occur, as there are plenty of talented users here happy to help.

Charlie


#11

Quick follow up question: I’m trying to edit the center section on the bar to tilt the vertical face inwards on an angle. I set up my angle guide, but when I go to select the face, any of the handles grabbed will not allow me to shift the top inwards to slope it. I’ve tried using the scale and rotation tool, and I can’t seem to get that top side to angle in. I could have sworn I did something similar with the scale tool before. Everything seems to affect the entire thing, and if I just try to select the top portion, it won’t tip. In case I’m making no sense in describing this, I want to do the equivalent of taking a vertical piece, and tip it so the top moves but the bottom stays.


#12

Or…I think I managed to get it angled, but then…it looks like this instead?!


#13

I am fairly certain this could be accomplished with strategic moves using the move tool and locking axis.
Native scaling probably not.

In this case I would just re-draw those parts of the model. (please see .skp )

SUV8_AmAd3809_07_26_2018.skp (826.7 KB)

Also, having the proper angles for the dovetail bit would be a great help to ensure that is correct/will fit.

Charlie


#14

I hesitate to ask anymore of you or any one else for that matter, but could you elaborate? For example, I go to step 3 of your process where you have 1 side of the original rectangle sloped, but not the other. How did you get the vertical face sloped in that case? I tried it on the other side still at 90 degrees with the move and rotate tool, and all I succeed in doing is elongating it along that plane or warping it in some fashion like the last image? In terms of learning the ropes, this one skill which should seem so straightforward is eluding me


#15

I’m taking a guess here, but you could make a guide line, use the rotate tool to get it at the correct angle, then use the Move tool to move the end of the face to snap on to the angle of the guide line. With some Shift key holding to make sure the face only changes in the red axis.


#16

Please don’t hesitate to ask, you are obviously trying to learn, as opposed to asking for others to do it for you.
I and others sometimes get busy…hence the delay in response(s).
Also, many learn from others asking questions, including those with lots of experience.
OK…back to model…selecting the line and using the move tool while the red axis is locked is how I accomplished the “raked” face on the model. (see pics)
You could also draw a line on the guideline and use the push-pull tool to accomplish the same. (not depicted)

Charlie