Jump to content


Photo

Eq Platform for $29.5

  • Please log in to reply
108 replies to this topic

#1 Ed Jones

Ed Jones

    Mercury-Atlas

  • *****
  • Posts: 2695
  • Joined: 06 Apr 2004
  • Loc: Sin-sin-atti

Posted 25 May 2008 - 03:13 PM

My latest scope needs a new eq platform because of the high CG. I'm almost done with this one except for some sanding, varnishing and bolting down the motors but so far it's cost only $29.5. That doesn't count the maple plywood I already had, ball bearings I had and some screws and leveling feet I need to get yet. It'll be done before the scope!
2 motors from Apogee @ $4 each
2 3 inch Newport SS rods @ $6.60 each
maple from Home Depot $8.30

Attached Files



#2 rmcpb

rmcpb

    Surveyor 1

  • -----
  • Posts: 1606
  • Joined: 16 Nov 2004
  • Loc: Blue Mountains, NSW, Australia

Posted 25 May 2008 - 07:29 PM

Ed,

What is the layout on the bottom board?

Looking good :)

#3 The bear

The bear

    Apollo

  • *****
  • Posts: 1116
  • Joined: 11 Feb 2008
  • Loc: rushville, indiana

Posted 25 May 2008 - 07:31 PM

yes ed enlighten us to your good owrk this would be ideal for a poor child like me.
doc
might have the motors already hehe

#4 Ed Jones

Ed Jones

    Mercury-Atlas

  • *****
  • Posts: 2695
  • Joined: 06 Apr 2004
  • Loc: Sin-sin-atti

Posted 25 May 2008 - 08:01 PM

Here is the bottom board. The 1/15 rpm motors from Apogee are CCW so they must go behind the north bearing. I drilled our the smaller tapped hole on th post to 4 mm to match the motor shafts on a lathe. The SS posts from Newport are 1/2 inch so the radius of the north bearing is 23.93. The CG above the middle of the board is 17.6 inches. Total height 4.25 in. If you want I can start another thread on how I made it.

Attached Files



#5 The bear

The bear

    Apollo

  • *****
  • Posts: 1116
  • Joined: 11 Feb 2008
  • Loc: rushville, indiana

Posted 25 May 2008 - 08:06 PM

yes please this would be very informative and excellent instructional to us all.
doc

#6 Jason D

Jason D

    Fly Me to the Moon

  • *****
  • Posts: 6656
  • Joined: 21 Oct 2006
  • Loc: California

Posted 25 May 2008 - 08:18 PM

How well does it perform?
Jason

#7 Ed Jones

Ed Jones

    Mercury-Atlas

  • *****
  • Posts: 2695
  • Joined: 06 Apr 2004
  • Loc: Sin-sin-atti

Posted 25 May 2008 - 08:52 PM

As you see it isn't finished yet but it's almost exactly like my first platform (which tracks great)except that I'm not going to knurl the Newport posts. I don't think it'll be necessary. I can always knurl it later if need be.

#8 Biff

Biff

    Mercury-Atlas

  • *****
  • Posts: 2638
  • Joined: 04 Sep 2005
  • Loc: Courtice, Ont.

Posted 25 May 2008 - 09:14 PM

If you want I can start another thread on how I made it.

Isn't this that thread?:question: And yes I'd like to see all the details too, namely how you setup to cut a VNS with such a tight tolerance for the radius!

#9 Ed Jones

Ed Jones

    Mercury-Atlas

  • *****
  • Posts: 2695
  • Joined: 06 Apr 2004
  • Loc: Sin-sin-atti

Posted 25 May 2008 - 10:34 PM

OK well I'll start from this thread.

My latitude is 39.25 degrees and my rocker box is 18 inches square so I started with a platform 19 inches wide and long.. Shown below is the cross section layout. The south bearing is 11.91 inches radius spaced 18 inches from the north bearing. The mid platform CG is 17.6 inches from the platform but my computation for the scope CG is 14 inches, 3.6 inches lower but I don’t think it’s a problem at all.

Attached Files



#10 Ed Jones

Ed Jones

    Mercury-Atlas

  • *****
  • Posts: 2695
  • Joined: 06 Apr 2004
  • Loc: Sin-sin-atti

Posted 25 May 2008 - 10:36 PM

I cut two boards with a 50.75 degree bevel about 4.5 inches X 20 inches. On the back side I tacked a ¼ inch scrap piece of plywood and measured from about where the tape is to a 23.93 inch arc from each side. I drilled a hole for a finishing nail to pivot on at that point

Attached Files



#11 Ed Jones

Ed Jones

    Mercury-Atlas

  • *****
  • Posts: 2695
  • Joined: 06 Apr 2004
  • Loc: Sin-sin-atti

Posted 25 May 2008 - 10:37 PM

On my table saw I bolted a ¾ inch piece of wood with my finishing nail pivot a little more than 24 inches from the blade. The blade was tipped at 50.75 degrees and lowered all the way down. I raised the blade a 1/16 of an inch at a time and swung the board into the blade slowly pivoting on the nail. I raised it another 1/16 th and repeated. Eventually the blade was above the board and it was roughed out. I then switched to a sanding disk and continued, moving the part a small distance into the disk each time until the radius was 23.93 at the midpoint. This makes beautiful smooth bearings (and I have fun doing this as well).

Attached Files



#12 Ed Jones

Ed Jones

    Mercury-Atlas

  • *****
  • Posts: 2695
  • Joined: 06 Apr 2004
  • Loc: Sin-sin-atti

Posted 25 May 2008 - 10:38 PM

I made a trapezoid board 19 in. long by 16 in . on one side and 19 in. on the other. I drew a mid-line perpendicular to the middle of the small side (on the bottom).

Attached Files



#13 Ed Jones

Ed Jones

    Mercury-Atlas

  • *****
  • Posts: 2695
  • Joined: 06 Apr 2004
  • Loc: Sin-sin-atti

Posted 25 May 2008 - 10:40 PM

I glued a block with a 50.75 deg. angle on the mid line for support.

Attached Files



#14 Ed Jones

Ed Jones

    Mercury-Atlas

  • *****
  • Posts: 2695
  • Joined: 06 Apr 2004
  • Loc: Sin-sin-atti

Posted 25 May 2008 - 10:41 PM

The south bearing comes out pointed so finding the mid-point is easy. I align the midpoint with the mid-line and glue and screw it together.

Attached Files



#15 Ed Jones

Ed Jones

    Mercury-Atlas

  • *****
  • Posts: 2695
  • Joined: 06 Apr 2004
  • Loc: Sin-sin-atti

Posted 25 May 2008 - 10:42 PM

With a square set to intersect the curve on the north bearing near the edge, I mark both sides then find the mid-point.

Attached Files



#16 Ed Jones

Ed Jones

    Mercury-Atlas

  • *****
  • Posts: 2695
  • Joined: 06 Apr 2004
  • Loc: Sin-sin-atti

Posted 25 May 2008 - 10:44 PM

I made an obtuse triangle to support the back, lined up the mid-point and glued and screwed it together as before. A support block on the other side would have been easier.

Attached Files



#17 Ed Jones

Ed Jones

    Mercury-Atlas

  • *****
  • Posts: 2695
  • Joined: 06 Apr 2004
  • Loc: Sin-sin-atti

Posted 25 May 2008 - 10:45 PM

I glued a 1.5 X 4.5 inch piece of maple to the inside of two 24 X 2.5 inch pieces. This is for mounting the motor. I drilled a ½ inch hole in two pieces of teflon and cut them into for bearings. 2 cross-pieces of maple were glued for strength. (I taped the posts and bearings in place temporarily to figure out where the cross pieces should go.)

Attached Files



#18 Ed Jones

Ed Jones

    Mercury-Atlas

  • *****
  • Posts: 2695
  • Joined: 06 Apr 2004
  • Loc: Sin-sin-atti

Posted 25 May 2008 - 10:46 PM

3 pieces of maple were cut to hold the bearings. The rear bearing block was easy, the other two were compound angles and it took a number of tries cutting pieces on a band saw to get the angles right so that the ball bearings races ran flat to the bearings. These little pieces were the trickiest part of the project.

Attached Files



#19 Ed Jones

Ed Jones

    Mercury-Atlas

  • *****
  • Posts: 2695
  • Joined: 06 Apr 2004
  • Loc: Sin-sin-atti

Posted 25 May 2008 - 10:50 PM

The rest is sanding, varnishing, screwing the teflon and motors down, wiring etc.

#20 ZachK

ZachK

    Viking 1

  • -----
  • Posts: 773
  • Joined: 20 Aug 2005
  • Loc: Israel

Posted 26 May 2008 - 01:35 AM

Thank you, I was planning something exactly like that and I think you gave me what I need to get going. I need to figure out how to do this without a table saw though. I have a jigsaw and a router.

#21 Mert

Mert

    Skylab

  • *****
  • Posts: 4222
  • Joined: 31 Aug 2005
  • Loc: Spain, Pamplona

Posted 26 May 2008 - 01:58 AM

That's a wonderful job Ed, very inspiring!!
Please let us know how it performs! :jump:

Regards and thanks for sharing

#22 reiner

reiner

    Ranger 4

  • *****
  • Posts: 364
  • Joined: 28 Sep 2005
  • Loc: Freiburg, Germany

Posted 26 May 2008 - 02:27 AM

Hi Ed,

can you tell me more about the motors? Are these DC geared motors? Could you post a link to where you bought them?

Thanks
Reiner

#23 Luigi

Luigi

    Fly Me to the Moon

  • *****
  • Posts: 5320
  • Joined: 03 Jul 2007
  • Loc: MA

Posted 26 May 2008 - 09:00 AM

Looks like a really nice, clean implementation! I've been planning to build at paltform once I get my shop set up (I'm moving) and this is a nice as design I've seen.

#24 Ed Jones

Ed Jones

    Mercury-Atlas

  • *****
  • Posts: 2695
  • Joined: 06 Apr 2004
  • Loc: Sin-sin-atti

Posted 26 May 2008 - 09:50 AM

The motors i used are 1/15 RPM AC timing motors CCW rotation 110 volt 60 hz 1.35 watts by Sonceboz. I just checked Apogee's website and sorry they no longer have them it seems. However Herbach and Rademan has this motor for $18.95.
here
It is clockwise however which means the motor must be mounted in front of the north bearing.

#25 reiner

reiner

    Ranger 4

  • *****
  • Posts: 364
  • Joined: 28 Sep 2005
  • Loc: Freiburg, Germany

Posted 26 May 2008 - 10:24 AM

Thanks for the information, Ed. I like your platform design.

R






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics