Welcome, Guest. Please login or register.

Username: Password:

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Messages - Tim C

Pages: [1]
1
Outreach & Events / Re: raffle for 2016 May 14 Astronomy Day?
« on: April 12, 2016, 06:53:27 PM »
I'd like to think on this awhile. Since we are going to the evening session at the Museum, it sounds like handouts and small prizes throughout the day may be better so it's not so complicated.

We could have the drawing later in the year at the Astrovaganza.

2
Mirror Grinding & Polishing / 8" donated mirror
« on: May 19, 2014, 07:04:35 PM »
I had the incident happen again where something created a scratch in the mirror I am working on. I am saddened, frustrated and fascinated all at the same time. I would like your help with this. I've never had this happen before and I have decided to the right thing here and track down what is causing this to recur. See image below, a little obscure....





I did feel the edge grab this time. The brighter blip in the photo is a sub surface bubble. My first impression is that this is the tiles at the edge of my tool that are breaking off. There is no chip at the edge of the mirror although the bevel has gotten much smaller. Rather than grossly rubbing the edges with a sharpening stone, I will take these to work and use my dental hand piece with a diamond disc to soften the edges and create a new bevel. In our dental lab we deal with different alloys that have specs like Brinell Hardness or Vickers Hardness. In the workshop I think it will benefit our knowledge base if we can specify the hardness of Pyrex and the tools we use. In this case it is sheet tile purchased from the local tile shops. They come in sheets that are tied together with a webbing I think is rubber or nylon. Would it be better to have a softer tool material in case of fracturing or would that matter? Once a small chip of tile releases onto the surface of the mirror, it tumbles and my theory is it gouges the surface. I am not sure if a softer tile would leave the mirror untouched. Anyway, enough of this for now.

Christopher cut a round of plywood for me to create a pitch lap on. Thank you Christopher (cool picture you drew on it). I covered this with epoxy. It turns out we can get the better epoxy from Home Improvement Center. I tried Home Depot and OSH. They both dropped carrying Devcon materials. They carry Loctite but in an 8-9 ounce package it is inferior. In fact at OSH I talked with an employee who agrees. Too bad customers and employees can't influence purchasing department heads. Too bad cost trumps quality these days.

We may pour a lap- I will check with Tom. We will continue with projects and I believe we will be looking at a Schmidt-Cassegrain this week and trying to clean or plan cleaning the optics. Please let us know if you will need testers and racks this week. Possibly much going on. You may come a little early if you want. I think Bill and the Museum is okay with that. Please, no sooner than 6:30 though, I think that is the time we okayed. I will put out an email if it is not. Thanks all! The workshop is going great. We had 10 last week. Let's keep going and please remember, let's leave Broder better than we found it.
T

3
Workshop Updates / Workshop
« on: April 07, 2014, 06:06:00 PM »
Greetings,
We are scheduling a workshop this Tuesday, April 8th at 7:30-9pm at the Broder Building across the walking bridge (over the creek) at The Museum of Natural History. We normally meet every Tuesday. This week we originally planned to be pouring yet another pitch lap, but we will put this off for at least one more week. Bring in your projects, inquiries or plans for all to see or talk about. Also, if you have questions regarding Astro imaging, bring those as well. In fact, we accept all inquiries related to telescope making, testing or imaging. You are welcome to come over and check us out. If you like what you see, let me know and I will include you on an email list notifying you when and where we meet.
Tim Crawford

Pages: [1]