Right Angle Bracket

Little Machine Shop offers this cast iron right angle bracket for use on MiniMills.
I bought one and immediately drilled it to accommodate my Sherline rotary tables.

It is much heavier than the aluminum bracket offered by Sherline.

I have used the cast iron bracket while roughing out the shape of a one piece spool, and find that the mill runs with noticeably less noise and vibration.

Posted in Fixtures, Milling, Work Holding | Leave a comment

More MiniLathe Tooling

I have used a Sherline lathe for about 9 years to make reel parts. In that time I developed many fixtures to facilitate lathe operation. Now that I am converting to a MiniLathe, new tools are needed.

Here its a turning bit based on a 3/8 round carbide insert. I will use it to finish the inside surfaces of spools.
Note 15 April: This cutter did not work, too much compliance. It dug into a bronze end plate and popped it out of a 3 jaw chuck.

I never used a magnetic base to hold indicators on the Sherline because the cross slide is made of aluminum. Now with a cast iron cross slide a magnetic base is handy.
I bought one, but found the stock arm (laying flat at right) to not have enough articulation. So I bought an additional swivel clamp and made two new arms.

The nut for my ER32 collet holder is grasped with a hook type spanner. To hold the flange, I bought a strap wrench.
But the strap material is too slick; it does not grip the polished flange. So I made a pin type spanner that fits unused holes on the spindle flange.

When the carriage is moved by its rack and pinion drive, there is no dial on the handwheel. So it made a holder for a dial indicator. It clamps to the lathe bed.
This holder can also be used as a carriage stop.

The same holder can be clamped in the tool post in order to read axial runout on a flat part.

Posted in Alignment, Fixtures, Turning | Leave a comment

MiniLathe Tooling

In 2015, I replaced my Sherline mill with a MiniMill (Little Machine Shop 3990).
The switchover was simple; I only had to make some special hold down clamps to continue using my Sherline rotary table with the new mill.

Now I have gone a step further and bought a MiniLathe. I chose MicroMark 84631 because it has 20/inch leadscrews on the cross slide and compound.
I locate the cutting tools by reading the dials at the handwheels, and I cannot work with a dial that has 62.5 divisions.

During lathe assembly, my attention was drawn to the system for adjusting the carriage gibs. It uses a combination of screws to push and pull the gib. None of these screws can be properly tightened because there is no solid stack of parts to tighten against.
So I removed the “push” set screws and put round shims under the gib and around the “pull” cap screws.

The tool post can clamp a bit as large as 5/8 inch, but you would have to do a lot of grinding to get the point down to the right height. I have many 1/4 inch bits from my Sherline lathe that I will continue using.
The brass shim here brings a 1/4 inch bit up to working height, and the shoulder centers the bit under the clamping screws.

It is obvious that the 3 inch chuck for the new lathe is more robust than the Sherline 3 jaw chuck.
But this extra heft comes at a price. Changing chucks is a matter of fiddling with studs and nuts in a confined space, rather than just spinning the chuck onto a spindle nose thread.
Further, I am heavily invested in Sherline chucks.
Significantly, the 4 jaw chucks can serve as milling vises, and can be quickly transferred to the rotary table on my mill. So I am highly motivated to continue using my Sherline chucks.

My solution is to buy an ER-32 collet chuck from Little Machine Shop. This allows me to chuck stock of up to 3/4 inch diameter through the hollow spindle.
When I first installed the collet chuck base on the spindle, I found the TIR on the taper to be about .0001 inch. Then I chucked a gage pin and read about .0002 inch TIR. (Note 9 April: Apparently this was luck. The second bolt-on measured .002 TIR on the taper. Later same day: I made several installs. One position consistently has .002 TIR, another .001, but the best position is under .0003 .)

The key to using my Sherline chucks is to leave the ER-32 chuck in place and make an adapter with the Sherline 3/4-16 thread.
This adapter is Duronze. It has 3/4 inch OD and a bore of a little more than 1/2 inch. Sherline sells a similar adapter but it does not have a bore.

Here is the adapter installed.
And here is a Sherline chuck mounted.

To keep chips from falling where they may, I tape transparency film to the stock chip guard and I have installed a piece of acrylic sheet in front of the carriage.
Note also a piece of Tygon tubing (split) around the exposed lead screw.

From LMS I bought several accessories: Jacobs chuck, live center, die holder, hand crank, and cut-off tool.
With all this, I believe that I have replaced all the Sherline lathe functions except for knurling.

Posted in Tools, Turning, Work Holding | 1 Comment

Cool Water

He’s a devil not a man,
and he spreads the burning sand with water.
Cool, clear water.
“Cool Water” recorded by Sons of the Pioneers (and many others)
Songwriter Bob Nolan

Got my anodizing process restarted after the move to New Mexico. This involved adding some plumbing to a garage utility sink for the cooling water loop.

One of the desired conditions for sulfuric acid anodizing is a bath temperature of 20C (68F). The DC supply is injecting power into the bath and the production of aluminum oxide is exothermic, so the bath is likely to rise in temperature during the 1 hour process time. If I would make a bath of 1 gallon or more volume, the bulk of the acid/water solution would limit the temperature rise. But I use only 1 quart of solution, making forced cooling necessary. My blog post of 22 Aug 2012 details the water cooled cathode.

In Lovells MI, my well water came out of the ground at 4 to 12 deg C year around (pump setting 50 ft, water table 1 ft). Overcooling was quite possible, so I had to supply the cooling water intermittantly while watching a thermometer. Probably made an on/off cycle every 5 minutes. Running the process took constant attention.

Here in NM we have been having warm weather for the season, 75F for several days. I am on city water, and the houses here are built on a slab. I do not know the building practices, but it seems that there is not much insulation between the cold water pipes and the concrete. When I first open a cold tap, the water may run at 24C for a while, gradually dropping to 18C. So there is not much temperature difference available for cooling. With a steady flow through the tubes, I could only keep the bath temperature down to 23C. Having more tubing in the cooling loop would probably allow lower temperature.

As for the resulting anodize layer, I cannot observe that it is adversely affected by the slightly higher temperature. And, I spend much less time watching the thermometer.

Another process consideration is that here at 5800 ft elevation, water boils at about 200F. So sealing the anodize layer has to be done at the lower temperature. My data sources say that anything above 170F should be OK, see blog post of 3 March 2012.



Posted in Anodizing/Plating | Leave a comment

Bronze Frame Reel – Final

The last drawing covers all the remaining parts for the click mechanism.
The kink in the spring biases the pawl for left or right hand wind. There is a blog post on spring bending, 13 June 2016.
The “pawl shim” is just a washer that spaces the pawl away from the back plate. It is supposed to help the pawl move freely. Info on this part was posted 8 May 2014.

Finally, here are material lists for the two reel sizes.

Posted in Plans, Spring | 1 Comment

Bronze Frame Reel – Pawl

The clicker has taken me more development time than any other reel feature, except possibly for the aluminum anodization process. I started out thinking that the pawl should be made from steel, since that is what I observed on commercial reels. I bought a “test kiln” so I could quench and temper.

Then I made a life test fixture, using a gearmotor.
I soon learned that modern plastics such as Delrin are much more durable than steel, in this application. I think it has to do with impact absorption, or “toughness”. Blog reference: 23 Aug 2011.

This is the present pawl configuration, a symmetrical pawl and an asymmetrical spring on symmetrical mounting posts.
Prior to this, I had made either the pawl or the spring posts asymmetrical. This recent configuration is the easiest for changing from left hand to right hand wind.

Here are the drawings for two sizes of pawl.

Notice the 20 degree angle on the flanks of the pawl tip. This is the pressure angle of the mating gear. It is not important when the pawl is clicking along in one direction, but it does help the pawl make a smooth reversal of direction.

Blog post on pawl fabrication: 22 Jan 2014.

Posted in Pawl, Plans | Leave a comment

Bronze Frame Reel – Ratchet & Bushing

The bushing and ratchet are made as one piece. I have not tried gluing two pieces of Delrin together because I don’t know of a suitable glue, and I have concerns about concentricity.
Terminology: Is it a ratchet if it allows rotation in both directions? It is made with a gear cutter, but is it a gear if it does not mesh with another gear? “Clicker wheel” might be the best term.

For the 3 weight reel, the part has a somewhat different form; there is no recess in the face of the gear (ratchet, clicker wheel, etc.). The reason is that the gear end of this part also serves as a thrust surface, and a recess in the 3 wt. part would be too small. All this leads to a different spindle mounting for the two sizes of reel.
See the post of 7 April 2016 for step-by-step instructions on making this part.

Posted in Bushing, Plans, Ratchet/Gear | Leave a comment