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4/08/2012

Observing Chair Work April 7th 2012

Yesterday was the local ATM session at Mat's house.  There was actually quite a bit going on.  There was a father and son, Tyler and Levi I believe, who are building their own 8 inch dob.  Yesterday they worked on the mirror box and that was interesting to watch.  Mat's son Jeff worked on regrinding his 8 inch mirror which was at F10 and which he wants taken down to about F5 or F6 I believe.  Josh, check the polish on his 4 inch and 8 inch mirrors and found that the polish needs to be done more on his 8 inch and that his 4 inch had some scratches in it that require further polishing.  I was there and with a lot of Mat's help and some from Josh, we worked through some issues on the chair and got the back leg put together.  Here are some images of the build of the chair. They won't be in any order of how we did this but I'll try to explain.


Here you can see the back leg of the chair that we assembled.  It is up and ready to go.  It is extremely strong and will hold weight quite well.  No worries there.  Working on the leg was one of the last things we did on the chair as it took time to drill the initial hole, then a larger hole to help the screw to go into the red oak which is really hard, and then we did a counter hold so the screw would be flush with the wood, keeping it smooth. 





 Here is the back and we cut the handle and I began to sand the inside of the handle by hand.  It worked quite well.  I like how the handle is back, allows for a good grip of the chair. 






 Next is the support for the front of chair and will be on the bottom.  In the plans it doesn't call for the support brace here to have its feet angled like the feet and to have them match for better support and aesthetics, we did that. I also sanded the bottom and Josh shared a sanding technique to get the bottom completely smooth. 






I also spent the first part of the session sanding the two notch legs to get them down so the chair can move. Mat finished as I was getting them uneven.  Here you can see them with the bottom brace before it was worked on.  Mat said that if you do this chair one thing he would do is to do the actual math to figure out where the angle of the holes need to be for the notches.  The plans are very good at that.  However, if I were to do this over, I would probably order from Catsperch their plans and hardware for $44.00 (the plans are just $25.00 and I am going to order them at some point just to take a look at them).  The plan and hardware can be found at this link about 3/4 to the bottom if not a little more. 








 One problem we continued to face with the chair is that the angle of the chair just wasn't right. To correct this Josh came up with the idea of making two wedges that go on top of the seat rest that we will secure to the them in the near future.  This fixed the angle issue quite nicely.  You can see it in the picture below.








Here is a close up of the two wedges on top of the seat support.  








And from another angle that is straight on.  Nothing fancy but it works.  Thanks Josh for the idea and cutting the tricky pieces. 







What's left is for us to round the back legs so the seat does all the way up, attach the front back rest to the front legs, put on the bottom support brace, redrill the holes for the foot rest and then I have a lot of sanding to so. I need to round the edges and just sand and trim.  I found that Catsperch uses thumbscrew  to secure and take off the bottom brace for transport so I'll probably do something similar. You can see that at this link (sorry, I don't want to post the picture that belongs to someone else).  Then I'll have to coat the chair so it holds up to dew and other moisture over time.  I am hoping for good weather next Friday or Saturday for observing and if so I'll be heading out to the Vernon site.  I did find another set of plans online for an observing chair and will post that link here in case someone wants to view those. 

Oh, my mirror is scheduled to be at Nova Optical for coating from Carl Zambuto so I'll more on that soon.