Making Degree Graduations
- seal killer
- Posts: 4696
- Joined: Sat Aug 18, 2007 10:58 pm
- Location: Ozark Mountains
Making Degree Graduations
All--
I would like to create about 20 one degree graduation marks on the adapter plate in my telescope pier project. They are not a requirement, but it would be nice to have them during setup of the telescope. They would be located on a 5" diameter (approximate) circle.
I don't really have a clue how to do it. But, I am thinking of mounting the adapter plate on the rotary table and using something in the spindle to create a mark about 0.125" long by moving the table that distance. The next mark would be created by cranking the table 1* and repeating the procedure. The marks would have to be deep enough to still show after the adapter plate is painted.
How might this actually be done?
--Bill
I would like to create about 20 one degree graduation marks on the adapter plate in my telescope pier project. They are not a requirement, but it would be nice to have them during setup of the telescope. They would be located on a 5" diameter (approximate) circle.
I don't really have a clue how to do it. But, I am thinking of mounting the adapter plate on the rotary table and using something in the spindle to create a mark about 0.125" long by moving the table that distance. The next mark would be created by cranking the table 1* and repeating the procedure. The marks would have to be deep enough to still show after the adapter plate is painted.
How might this actually be done?
--Bill
You are what you write.
Re: Making Degree Graduations
I think you've basically got it. A broken drill bit or end mill could be ground to provide the cutter. The business end (looking down the bit axis) would look like a triangle with one shorter side, and maybe a bit of rake back toward the short side. The point opposite the short side is the cutting edge. Lock the spindle so it can't rotate (may have to rig something, doesn't need to be perfect or terribly robust) with the point oriented roughly "square" (or "normal" or whatever you want to call it) to the edge you want to score. The in-feed should be radial to the rotab rotation axis. With the plate centered on the rotab axis, make the mark by "stroking" the quill. Set a stop so you get repeat length of stroke, and feed in till sufficient depth achieved. In feed will likely start on the order of a few thou per stroke and see where it takes you. As you get deeper, you may need to reduce in-feed per stroke. Rotate and repeat till done. Extra points for making every 5* multiple mark ~10-20% longer to easily differentiate. More points still for a vernier implementation.
Russ
Master Floor Sweeper
Master Floor Sweeper
Re: Making Degree Graduations
A slitting saw on an arbor makes very nice graduations, and I expect would be much quicker than a single lip engraving type cutter. It's also nice to make every 5 deg mark somewhat longer, and the 10 deg marks longer yet.
Wayne
Wayne
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- Posts: 3803
- Joined: Wed Feb 21, 2007 9:21 pm
- Location: Vallejo California
Re: Making Degree Graduations
The ideal tool would be this http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 2426wt_849
I just bought 10 for little change.
They come on different included angle points.
This is much better that a slitting saw, but a very thin and small diameter should do fine.
Maybe more durable.
Those styluses require high RPMs.
I just bought 10 for little change.
They come on different included angle points.
This is much better that a slitting saw, but a very thin and small diameter should do fine.
Maybe more durable.
Those styluses require high RPMs.
There are no problems, only solutions.
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Retired journeyman machinist and 3D CAD mechanical designer - hobbyist - grandpa
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Retired journeyman machinist and 3D CAD mechanical designer - hobbyist - grandpa
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- Posts: 775
- Joined: Sat Jan 04, 2003 10:45 am
- Location: Albuquerque NM
Re: Making Degree Graduations
I did that for a project that the kids do school. I just took a 1/8" carbide burr that had been
"used up" and ground a point on it, put it in the spindle and, in our case, traversed the
table to make the scale. It was just a linear scale. So the rotab would do for the arc.
...lew...
"used up" and ground a point on it, put it in the spindle and, in our case, traversed the
table to make the scale. It was just a linear scale. So the rotab would do for the arc.
...lew...
- mechanicalmagic
- Posts: 1431
- Joined: Sun Nov 04, 2007 12:11 am
- Location: Pleasanton, CA Land of perfect weather
Re: Making Degree Graduations
Bill,
You can use a fly cutter in the horizontal axis of your mill. Grind a cutter with a ~90* included angle on the periphery. Too narrow a groove will try to suck up paint.
Dave J.
You can use a fly cutter in the horizontal axis of your mill. Grind a cutter with a ~90* included angle on the periphery. Too narrow a groove will try to suck up paint.
Dave J.
Every day I ask myself, "What's the most fun thing to do today."
9x48 BP clone, 12x36 lathe, TIG, MIG, Gas, 3 in 1 sheetmetal.
9x48 BP clone, 12x36 lathe, TIG, MIG, Gas, 3 in 1 sheetmetal.
Re: Making Degree Graduations
Some people just use a lathe threading or similar Vee shaped tool to do the scribing.
Don Young
- seal killer
- Posts: 4696
- Joined: Sat Aug 18, 2007 10:58 pm
- Location: Ozark Mountains
Re: Making Degree Graduations
Russ and Wayne and Jose and Lew and Dave and dly31 and All--
Lots of ideas. Thanks!
I am going to experiment on some scrap.
--Bill
Lots of ideas. Thanks!
I am going to experiment on some scrap.
--Bill
You are what you write.
Re: Making Degree Graduations
I'm with Jose. These are done with a ho-made engraving cutter--D-cross section, 30 degree included angle. Fine for aluminum--little delicate for steel. I like the "crisp" end of the grad line you get with a cutter like this, as opposed to the "tail-out" termination you get with a slitter or fly cutter. But, there are many ways to do do this and it's a matter of personal preference and expedience. Good luck with your grads!
Regards
Bob
- seal killer
- Posts: 4696
- Joined: Sat Aug 18, 2007 10:58 pm
- Location: Ozark Mountains
- seal killer
- Posts: 4696
- Joined: Sat Aug 18, 2007 10:58 pm
- Location: Ozark Mountains
Re: Making Degree Graduations
Jose--
How fast do you have to turn those styluses?
--Bill
How fast do you have to turn those styluses?
--Bill
You are what you write.
Re: Making Degree Graduations
Almost impossible to drive them too fast---considering they have an almost zero diameter. 20,000 rpm wouldn't be unreasonable, and in aluminum you could justify more than 50,000.seal killer wrote:Jose--
How fast do you have to turn those styluses?
--Bill
Harold
Wise people talk because they have something to say. Fools talk because they have to say something.