Building a Micrometer Stand Part 2

Here’s the completed project.

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Holding Screw

The instructions call for the holding screw to be machined from a piece of brass or plastic so as to not mar the micrometer. What I ended up doing as making it a steel knurled nut instead. I threaded the center, then ran a nylon screw through the center.

My original plan was to melt the nylon screw into the nut so they would become one piece. I envisioned cutting a couple of groves on the top to make this happen. In the end that wasn’t necessary, as it works just find by hand-tightening the plastic screw then using the nut to lock it into place.

Knurling on the Mini Lathe

The mini-lathe has trouble dealing with the forces involved in knurling steel. I had to replace the lever on my quick change tool post with a nut that I could crank down hard using a long wrench.

The last time I knurled something was over a decade ago so I’m sure that I’m forgetting a step or seven, but it worked out well enough to be usable.

Tilt Adjusting Screw

I made this out of a single piece of 1/2” cold rolled steel. The plans call for 3/4”, but I already have 1/2” chucked up from the previous part. And really, 3/4” seems overly large.

In theory I could have used a piece of threaded rod that was glued into place, but that’s kinda cheesy. So I did turn it down to the correct screw diameter. Actually I went a thou or two under on the theory that if my cheap digital calipers were off it was better to err on the low side. (No, I don’t actually own a micrometer. The stand is a gift.)

Cutting the Threads

The first attempt was a dismal failure and I bent the part. Not willing to start over, I straightened the shaft using repeated blows from a lead-filled, rawhide mallet.

That taken care of, I tapered the end so I would actually stand a fighting chance. I normally don’t like doing it because changing the angle on the compound slide it a pain in the ass. But after doing so, the threads were easy to cut.

I used a die holder from Little Machine Shop so I didn’t need to remove the part from the lath. This has always proven to be much more reliable for me than using a hand-held die holder.

Swivel Screw

I’m not entirely sure why I needed to make this screw (besides the learning experience). It seems to me that a normal set screw would have done the job equally well. Is there really any advantage from only threading half of the screw?

Parting Off

Trying to part this off using the lathe’s parting tool was silly. It snapped long before I got close to finishing the cut.

Thankfully I had a small vise. So I racked it up and finished the parting operation using a Dremel’s cutoff wheel. Then I cut the slot for the screw driver using the same tool.

Finishing

I used Birchwood Casey Gun Super Blue to add a protective finish. It’s always worked well for me so I haven’t tried anything else.

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Building a Micrometer Stand Part 1

These plans were inspired by Useful Machine Shop Tools to Make for Home Shop Machinists by Stan Bray. Unfortunately the plans and instructions in that book are woefully incomplete, often missing key steps and measurements. Furthermore, they use British screw sizes that are not available in the US. So while the book is useful, I think this will help beginners like myself.

Where appropriate I’m including links to my local hardware store. Even if you don’t buy from them, you at least know what to look for.

Micrometer Stand

Micrometer Stand Plans PDF
Micrometer Stand Plans Fusion 360

Conversion Notes

When I originally did my conversions, I did a direct mapping between British BA sizes and US numbered sizes. Then I realized that some numbers sizes such as #5 and #12 don’t actually exist. Yes, you can buy tap and die sets for those sizes and make your own screws. But they are hard to find and not worth the effort. So I went back and only used #4, 6, 8, 10, and 1/4”.

My next mistake was using UNF or fine-threaded screws. In my defense, these are closer to the TPI used by British BA screws. And I already had the necessary taps and dies in my starter set. But UNF screws are hard to come by. Apparently UNC or coarse-threaded is considered the “general purpose” screw design and UNF is only used when vibration is a concern.

Beyond that I had to guess at some measurements. Thankfully the book is printed almost 1:1, so I should be pretty close to the original.

Body

Ideally the body is milled from a single piece of metal. If you don’t have access to a mill, or don’t want to waste the metal, it could be constructed from three pieces that are bolted together.

Milling

Set the part on parallels that are high enough that you won’t cut the vise when cutting the bottom of the U-shape. This doesn’t leave much metal to grab, so center it in the vise and crank it down hard.

Start at one edge and cut thin slices forward and back until you reach the correct depth. I used a 1/2 end mill for this. Lock the X-axis while performing these cuts so the table doesn’t move.

Once the right depth is reached, lock the table height. This is important because you want the bottom to be even all the way across. (Though honestly, nothing touches it so it isn’t really that important.)

Unlock the x-axis, move the cutter over a bit, then relock it. Take off a slice using the the side of the end mill by cranking on the Y-axis handle. Make sure this is a conventional cut, not a climbing cut, or you could yank the part out of the machine.

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Repeat until you’ve reached the other end of the part.

Holes

The holes on the bottom are counter-sunk at 82 degrees to match the US flat-headed machine screws. If you don’t have a counter-sink, it’s not important. There’s enough clearance for pan-headed screws.

The holes on either end are critical. If you accidentally drill one of them off-center, move the other one over by the same amount so that they are lined up with each other. (If I had a long enough drill bit, I would have drilled both holes at the same time. These are called “aircraft” drill bits.)

Cleanup

A belt sander is really useful for rounding over the sharp corners. If you have a narrow strip sander, it can do the inside as well. Otherwise there are always files.

Base

The recommended size is 3” x 1.25” x 1/2” thick. Really it can be any piece of scrap that is wide enough to lend stability to the stand.

Transfer the holes from the base to the body. Transfer punches can help with this. Note that the cheap Harbor Freight set won’t mark steel very well, if at all. But if you are using wood or aluminum then it should be just fine.

If you are 100% perfect in the placement of the holes in the body, the transfer punches aren’t necessary. (But if you are that good, why the hell are you reading my blog?)

The body is supposed to be centered on the base. Unfortunately I drilled one of the holes too big, so I had to move it over a bit. Then I broke a tap and had to move the holes over a second time. Now I have a convenient place to stamp my initials or attach a clamp.\

Slightly counter-sink the holes, it will make starting the tap easier. You may also want to use a slightly larger drill. This will reduce the “thread engagement”, weakening the holding power but also lessening the torque needed to tap it.

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Support

The support is the piece that actually holds the micrometer. Again this could be constructed from 3 parts but it is better to mill it from a single block.

Milling

Setup is easy since you are cutting parallel to the vise. I’m not sure what the best setup for this is, so I made the top of the part flush with the top of the vise.

Rather than following the plans exactly, I chose an end mill that the was slightly wider than my micrometer and ran it straight down the middle, leaving a shallow slot. Raise the table, then repeat until the correct depth is reached.

While doing this you’ll want to lock the Y axis. This is a pretty easy cut, but there is no sense taking chances that the table will shift.

Holes

The holes on either end are critical. They must be lined up perfectly with each other or the part won’t rotate correctly. Drill them deeper than the plan calls for and you’ll be less likely to break a tap.

Speaking of which, be really careful tapping these holes. The #6 tap is easy to break and you can’t simply move the holes like you did with the base. (So yea, I did have to make a second support. Also, #6 taps are cheap so buy several when you do break it.)

Technically speaking you should use a taper tap to start, then finish the blind holes with a bottoming tap. But again, I drilled the holes deeper than necessary and just used a generic plug tap. Use plenty of tapping fluid, it will help to wash away the chips.

The location of the hole on the side isn’t critical. You can even have multiple if you want to hold things other than a micrometer.

Part 1 Completed

From top to bottom is the support, body, and base. In my next post I’ll talk about machining the custom screws.

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BA to UNC (US) Screw Conversion Chart

For converting British small screws (BA) into equivalent US screw sizes.

BA Screw

Closest US Screw

Clearance Hole

Size

TPI OD (in) Size
OD (in)
Tap Drill
(in)
Close Fit
(in)

Free Fi
(in)

BA0 25.40 0.236 ¼-20
0.250
7
0.201
F
.2570
H
.2660
BA1 28.22 0.209
BA2 31.36 0.185 #10-24
0.190
25
0.150
9
.1960
7
.2010
BA3 34.79 0.161 #8-32
0.164
29
0.136
18
.1695
16
.1770
BA4 38.48 0.142 #6-32
0.138
36
0.107
27
.1440
25
.1495
BA5 43.05 0.126
BA6 47.92 0.110 #4-40
0.112
44
0.086
32
.1160
30
.1285
BA7 52.92 0.098
BA8 59.07 0.087 #2-56
0.086
50
0.070
43
.0890
41
.0960
BA9 65.13 0.074
BA10 72.57 0.067
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Fabris – Drills for Plate 24

This play is essentially the same as plate 23, but it starts on the outside.

Plate 24 – Common Fencer 1a

  • Both fencers start in 3rd on the outside.
  • The agent provokes a response by beginning to constrains the patient by turning the wrist into fourth
  • With a step, the patient disengages to the inside and attacks in fourth.

Plate 24 – Common Fencer 1b

  • Both fencers start in 3rd on the outside.
  • The agent provokes a response by beginning to constrains the patient by turning the wrist into fourth
  • With a step, the patient disengages to the inside and constrains in second. This puts him in narrow measure

Plate 24 – Fabris 1

  • Both fencers start in 3rd on the outside.
  • The agent provokes a response by beginning to constrains the patient by turning the wrist into fourth
  • With a step, the patient attempts to disengage to the inside
  • Agent lowers the body to collect the patient’s point on his hilt while thrusting in third under the sword.

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Plate 24 – Fabris 2

Use this if the patient allows the original constraint to be completed.

  • Both fencers start in 3rd on the outside.
  • The agent constrains the patient in fourth.
  • The patient tries to free his sword using a disengage
  • The agent steps into narrow measure, constraining on the inside in second.
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Fabris – Drills for Plate 23

This play specifically says the fencers are in misura larga or wide measure. Loosely speaking, this is the range in which you can attack with a single step.

Plate 23 – Common Fencer

This drill will work better for the patient if the agent is an angled third. Any actions of the point take longer because it has so much further to travel. You can make it even worse by standing upright as shown in this illustration from L’Ange.

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  • Both fencers start in 3rd on the inside.
  • The agent constrains the patient by turning the wrist into second
  • Patient attacks below the agent’s sword by lowering the point [If he doesn’t react, see Plate 22 Fabris 1a]
  • Agent lowers his own point, turning his hand into fourth.

Plate 23 – Fabris

Using the extended third of Fabris allows the agent to make a smaller motion for both the constraint and the counter-thrust.

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  • Both fencers start in 3rd on the inside.
  • The agent constrains the patient by turning the wrist into second
  • Patient attacks below the agent’s sword by lowering the point [If he doesn’t react, see Plate 22 Fabris 1a]
  • Agent lowers his own point, turning his hand into fourth.

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Fabris – Drills for Plate 22

Prior to attempting these drills you should be familiar with the drills on plate 21.

Plate 22 – Fabris 1a

  • Both fencers start in 3rd on the inside.
  • The agent constrains the patient by turning the wrist into second
  • Patient doesn’t react [If he does react, see plate 23]
  • The agent performs a straight feint, rotating his hand clockwise and extending the shoulder and body.
  • Patient doesn’t react [If he does react, see below]
  • The agent continues forward, rotating the into fourth and stepping as necessary as per illustration 21.

The constraint isn’t mentioned on this page. You need to go back to the previous page, where it says that,

If you want the feint to be successful, either wait for a movement of the opponent or first find his sword so as to render him incapable of using that line to attack you.

    Failure to do this gives us Plate 21, Fabris Fencer 1 where in the patient wins.

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    Plate 22 – Fabris 1b

    This is an improved version of Plate 21, Common Fencer 1b.

      • Both fencers start in 3rd on the inside.
      • The agent constrains the patient by turning the wrist into second
      • Patient doesn’t react
      • The agent performs a straight feint, rotating his hand clockwise and extending the shoulder and body.
      • Patient parries
      • The agent drops his tip to disengage and avoid blade contact, raises it on the other side, and thrusts in 3rd over the arm, stepping as necessary, as per illustration 22.

      During this drill the agent must continually move forward with his arm, then shoulder, then body, and finally with his foot throughout the feint, disengage, and subsequent attack. If there is any hesitation, as if performing distinct actions rather than one fluid motion, the attack can be interrupted.

      For the disengage itself, it is not always necessary to agent move the sword swideways. The patients parry will move his sword to the other side, so the agent merely has to concentrate on dropping and raising the point.

      Loosening the hand in order to drop the point is preferable to bending the wrist. Especially when in the extended 3rd, where in you only have to drop a very small distance.

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      Plate 22 – Common Fencer 2

      • Both fencers start in 3rd on the inside.
      • The agent constrains the patient by turning the wrist into second
      • The patient disengages to the outside with a step
      • The patient thrusts in 3rd over the arm

      Plate 22 – Fabris 2

      • Both fencers start in 3rd on the inside.
      • The agent constrains the patient by turning the wrist into second
      • The patient disengages to the outside with a step
      • The agent counters with a straight thrust in third over the arm as shown in illustration 22.

      Timing: The agent starts his counter-thrust as soon as the patient’s point crosses the vertical plane formed by the agent’s quillon. Any sooner and you’ll be on the wrong side, any later and you may not have enough time.

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      Fabris – Drills for Plate 21

      It is vitally important that you do not skip over the “common fencer” drills. These are not drills of the incompetent fencer, but merely one who hasn’t had the additional instruction from Fabris. So it is something that you would see in the marketplace.

      The reason you specifically need to practice these exercises is so that your partner can learn to counter them using the techniques of Fabris. If you cannot reliably use them, then your partner won’t know if he is performing the counter correctly or not.

      These are the first partner drills given to us by Fabris. (Though he does hint as possible partner exercises in earlier plates, especially on the guards.)

      Plate 21 – Common Fencer 1a

      • Both fencers start in 3rd on the inside.
      • The agent performs a straight, fast feint.
      • The patient counters with a parry.
      • The moment the blades touch, the agent disengages under the sword and attacks in second from below, lowering the body for safety. See illustration 34.

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      Plate 21 – Common Fencer 1b

      • Both fencers start in 3rd on the inside.
      • The agent performs a straight, fast feint.
      • The patient counters with a parry.
      • The moment the blades touch, the agent disengages under the sword to the outside and attacks in third over the arm as shown in illustration 22.

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      Plate 21 – Fabris Fencer 1

      • Both fencers start in 3rd on the inside.
      • The agent performs a straight, fast feint.
      • The patient counters with a straight thrust in fourth, picking up the agents point in the process as shown in illustration 21.

      It is vital that the patient concentrate on the counter-thrust itself. If he overemphasizes the parry, it will throw his point offline which is exactly what the agent wants to happen.

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      Plate 21 – Common Fencer 2a

      • Both fencers start in 3rd on the outside.
      • The agent advances while disengaging to the inside.
      • The patient counters with a parry.
      • The moment the blades touch, the agent disengages under the sword and attacks in second from below, lowering the body for safety. See illustration 34.

      In this and the next drill, the agent can use a constraint or blade contact to further encourage the patient to parry.

      Plate 21 – Common Fencer 2b

      • Both fencers start in 3rd on the outside.
      • The agent advances while disengaging to the inside.
      • The patient counters with a parry.
      • The moment the blades touch, the agent disengages under the sword to the outside and attacks in third over the arm as shown in illustration 22.

      Plate 21 – Fabris Fencer 2

      • Both fencers start in 3rd on the outside.
      • The agent advances while disengaging to the inside.
      • The patient counters with a straight thrust in fourth, picking up the agents point in the process as shown in illustration 21.

      Timing: The patient starts his counter-thrust as soon as the agent’s point crosses the vertical plane formed by the patient’s quillon. Any sooner and you’ll be on the wrong side, any later and you may not have enough time.

       

       

       

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