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.

The Project Begins

The Project began at the school table this morning. We are going to grind a 6" f/8 mirror and put it in a Dobsonian mount. I began by telling them that we will be able to see the a couple of miles of the Moon at a time, see the divisions in the rings of Saturn, and the phases of Venus to build their excitement.

We then went over the basics of grinding the mirror. I emphasized the precision of the mirror, which made Anna a bit nervous since she is fearful of making a mistake. I relieved her anxiety that the errors between 3 careful grinders will average out and should actually produce a mirror with greater precision.

We then went over the need for a very stable stand to grind the mirror on. We followed this up with a trip to Lowe's to get the materials to build our stand.

Tomorrow I will post pictures of the stand and its building.

As Jack Horkheimer says, "Keep looking up."