machine
12 Inch Slip Roll
Finally, I found a high quality small slip roll.
This is the highest quality 12 inch slip roll you will ever see, use or own. I just unpacked this new sheet metal forming machine and will soon have a full report in The Hobbyist Machine Shop.
This product is so exquisite compared to the Chinese junk I once owned for a few days, I can hardly stop starring at it. This picture barely does it any justice. The complete report will show a lot more close up pictures.
This is the model PR12W made by Accu Cutter. A definite high end machine tool. Well priced for the professional high quality US made tool that you see here.
I haven’t cleaned it up at all at this point. It still has a light coat of white grease which will be seen in all the “first look” photo’s taken. I will show how it was packed for shipping which was also first class double boxing.
UPDATE: Full writeup, more pictures in The Hobbyist Machine Shop – Under the “Workshop” tab.
Do You Need The Balls?
There is a common conception in the amateur machinist world that ball or roller bearings are always the preferred selection to bushing or solid surface bearings. That is not always the case. Machine engineers, of all people, should know it always depends on the application. There are many applications where ball bearings are contra indicated, meaning they should not be used. Some of those reason can be as simple as cost over performance, excessive noise or the possibility of bearing contamination in harsh environments.
The primary benefit of using a ball bearing over other types is the greatly reduced drag due to its small rolling surface contact point. Their use is preferred when low friction is a high priority and other factors like low noise is not. They will reduce power requirements, help reduce friction heat and provide long periods of operation. If they are properly sealed, they will reduce maintenance. The best, high quality ball bearings can reduce run out and take thrust loads. These are worthy goals but sometimes are higher goals than necessary.
To quickly get to my point, I’ll examine the bearing needs for the lead screws on all the axis of a small manual mini lathe. First, do radial ball bearings “increase machining (position) accuracy” on any of the calibrated axis including the Z axis main feed screw over a bushing type bearing? The answer is an absolutely no.
This is because the linear slide position accuracy is a function of axial (not radial) screw loads affecting the amount of compression/expansion of the lead screw, drive nut thread engagement, drive nut mounting rigidity, thrust surface material and screw shaft bearing end play. This as combined is commonly called backlash. Minor drive screw side play (run out) is not a factor.
Radial bearing loads… Continue reading
It’s The Little Things
The small bits and pieces are going to get me. All home machinists know the purchase of the major machines is the big money decision in getting started. No doubt about that. But there is something more insidious to my available funds.
What gets me after the big purchase is the constant cash flow required in getting all the little bits and pieces I need to get projects completed. It’s not really any different than any other hobby. All my other hobbies I enjoy seem to be cash eaters too. Maybe I should take up whitlin’ if I can find some free wood.
I was just sitting here at the computer ordering a few restock parts from McMaster-Carr. I am updating my starter and countersink drill bits both 60 degree and 82 degree. They generally last a long time but mine have seen better days. I’m getting a five piece set of each angle. I need a couple of #2-56 taps, two because I’ll break the first one. With two I won’t break either. That’s the way it works, I know.
OK, throw in some #2-56 flat head machine screws, only a few bucks…
What happened? (!!) That total can’t be +$80.00! Wow, its right. My theory is correct. It’s the little things that bite me the hardest.
Lens Plate
My daughter is a professional photographer working for a large commercial corporation. Some of the studio cameras use lenses that mount on a lens board as you see here. That is not a real piece of board, but rather a cast aluminum plate. I think the idea is to make lens changes and adjustments easier.
On this one someone bought the lens board with a hole that was too small. Maybe they got a deal? You can always make a hole bigger right? Problem is most people do not know how to make the hole bigger. If they know, they probably don’t have the proper tool.
I was given another lens board with the hole being much larger than necessary. “Just make the small hole half way bigger than the large hole.” I was told. I love those accurate working dimensions. Ha!
It was dang close to being a 2 inch hole I suspected I needed. I bored the small one out to about 1.995 inches. I was actually thinking 2 inch but short is better than taking too much.
My daughter took the lens board to work and sure enough the hole was still too small. “It needs just a hair more, Dad!” was her request. Uh… “What color hair, kinky, curly or straight?” I went for red, curly.
In the pix I went out to 2.010, so I’ll see if I got the color right…
The Hobbyist’s Quandary
I have a decision I should make about building live steam locomotives. It’s not one I have to make but not making it is a decision in itself. In other words I am not at a stopping point where I have to make a decision to move on, but rather shall I continue where I am going or change direction. It is not a dilemma as none of the choices are truly unsatisfactory.
So I went back and read some of my own writings from around year 2003 that I posted in my The Hobbyist Machine Shop website. Hard to believe I started my publishing seven years ago. I see that most of my interests and goals have not changed in all that time.
Back then I said my plan was to design and build my workshop and machine tools to a size where I could work on live steam model locomotives in a scale size of ½ inch to ¾ inch. Mission accomplished. What has not been accomplished is actually completing any projects of that type. I do have some work done in ¾ inch scale on the Pennsy A3 Locomotive but the nearly three year layoff didn’t speed that project along.
What I noticed from seven years ago is that I said my primary interest was in ½ inch scale with ¾ inch my upper limit. I feel that is still true. So why did I start building in ¾ inch scale? There are several good reasons.
Number one is the outstanding publication of engine projects in that scale by Kozo Hiraoka. Second is the fact the parts are large enough that my PN is not much of a problem as it would be with very small parts. Third, the scale locomotives look wonderfully massive, complex and… Continue reading