Friday, August 28, 2009

The Stand

Here is the completed Grinding stand. I know that it looks like it is leaning but it really is plump and level. The Stand is made from an old paint bucket that I was using as a doose bucket on my outdoor brick oven, concrete, 4" PVC pipe, a 6" 4x4 timber, and an 18" table top blank purchased at Lowe's.

One of the wonders of building such a precise astronomical insturment is how roughly some of the tools and equipment can be built. Our stand is largely built from scronged items that I already had on hand. Before the kids and I went to Lowe's I took stock of what I already had, so that I could get by as cheaply as possible.

When we got to the store, we went straight to the plumbing department. I really wanted to get a galvanized pipe and flange for the pedastal, but I didn't want to spend as much as that was going to require. My next choice was oak, but again price intervened. Ultimately, I decided on the PVC which cost less than $7.

The first step was to cut a 6" 4x4 timber (it had been a part of a fence that I took down). We then planed the corners off so that it would fit inside the PVC pipe. This timber is what the top is secured to. We then mixed a bag and a half of mortar mix left over from my oven project. It had set around for nearly a year and become quite compacted.

Once the mortar was mixed, we filled the bucket with the mortar and then set the pipe in, which we also filled leaving room for the 4x4 block. We used a level to make sure everything was properly plumbed and leveled. All of the weight makes the stand very stable, so that it will not be wobbly when we begin grinding.


I then attached the top using 4 counter-sunk screws, which can be seen through the mirror blank. The cleats, which hold the mirror, is from a flower stake from my garden. The cleat screws are also counter-sunk.

The only thing left to do with the stand is to seal the top. When using the abrasive charges for grinding, water is used as a lubricant, and I am sure that the glue used in the top is not waterproof.

We will using Kilz, left over from painting the bathroom for the sealer. Once that is done, our stand will be completed.

Also, the mortar does not adhere to the PVC, so there is no need to be excessively careful when filling the PVC pipe.

When doing a project like this, do not be afraid to use what you have on hand. Remember the goal is not a beautiful stand, but one that is serviceable for the intended use.

Next week, we will begin "hogging out" the mirror blank and making the grinding tool. Stay tuned.

1 comment:

  1. can't wait to find out what "hogging out" means---sounds like something to do with food... :)

    ReplyDelete

Naming a Blog

Choosing a name for a blog is very difficult and fraught with dangers, but in consulting with Mary Kathryn, my dear bride, we decided on "Kenning through Astronomy Divine."

The name comes from Meditation 6 by Edward Taylor, a New England Puritan, pastor, and physician. Every week he walked hunderds of miles to tend to his flock and care for the sick, and he still had time to be a prolific writer.

About Our Project

In 1978, when I was 12, I bought a book on telescope making at Davis Planetarium in Jackson, MS. It started me on a quest to grind my own telescope mirror. Two years later I order a 6 inch mirror blank and abrasives from Edmund's Scientific only to be crushed when the blank arrived without the abrasives. Edmund's had stopped carrying them. Over the next 30 years, I had thought about grinding that mirror that I had been carrying around for so long. Now as part of a homeschool Astronomy class with my children, we will complete a project 32 years in the making. I hope you all enjoy following our progress in this. We hope that it culminates in February or March with a West Virginia Star Party that will include some of my nieces and nephews.

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