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Restoring and Repairing
Slide Rules and Notes


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This page contains notes of efforts and techniques in the restoration of slide rules.and is under development.

General Notes on Repairing Slide Rules

  • Missing Cursor Springs - Mainsprings for Pocket Watches may be bought and used to replace a missing tension spring in most cursors. Ebay has many sellers listing packages of vintage main springs of various thickness and widths. These are all tempered into a spring steel state, so if you try and shape the spring with a tight bend, it will snap. You have to stretch the spring out and hold it over a flame until it turns yellow then let it air-cool. This will anneal the metal allowing you to make the bends to fit into a cursor.
  • Pickett Microline cursors - These cursors are two identical parts (hermaphroditic) that mate with each other. the male and female features are a press fit, Many times the flat spring is lost and can easily be replaced. Sometimes it is possible to separate the two halves, but most often the two male posts snap off in the receiver hole. I've tried 5-minute epoxy to assebled the pieces, but it didn't hold. Possibly a cyanoacrylate (super glue) might stick.
  • Wrinkled manuals - You can use a clothes iron with a low steam setting to remove the wrinkles on folded manuals or dog-eared book pages. Place in a zip log bag with a cardboard backing to prevent further damage.
  • Celluloid scales lifting (delaminating) from wood stock
    - I have the best sucess using 5-minute epoxy with a clamp to put the scale back in place. Clean up with denatured alchohal while the residue is still sticky and not yet cured.
  • Split wood stock - A white wood glue such as Elmer's or Tightbond can be used to close the crack in the stock along with a suitable clamp. Clean the excess with a damp cloth. In some cases, this also works for deklaminated cellulois scales (but I find 5-minute epoxy quicker to finish the job).
  • Dietzgen cursors - Most Dietzgen models have th same stock dimensions as the equivaleny K&E, so any K&E cursor (OEM or ISRM Replica) should work on those slide rules.

Frankenrules - Swapping cursor onto unrelated models.



K&E 1930 All Glass Cursor vs Ricoh 1960 All Plastic Cursor

Most of the Relay/Ricoh/SIC cursors will fit K&E and Dietzgen stocks. The gap between the blocks is wide enough to accomodat K&E 20" slide rules.


The early Dietzgen 1746
slide rule shown above has a restored cursor needed to replace the crumbling original from 1926. The early lens and metal lens brackets were retained, a SIC (Relay) cursor spacers were modified, drilled and tapped with 1-72 UNF threads, to accept new screws (K&E uses 1-72's). This gives this 'old soldier' a new life.


Nestler 0291 and 0292 Duplex w/ Pickatt Cursor

We received a 0291 that had a missing cursor. In rummaging around the stacks of duplicate and loaner slide rules I discovered that the Pickett wide body Microline plastic stocks had the same dimensions. To make your high-end Nestler functional, you can get an inexpensive Pickett 120 or 140 and carefully separate the pressed-together hermaphroditic Pickett cursor apart. you might snap off one or both of the male bosses. I have used various advesives like a cynoacrolate or 5-minute epoxy, but I think drilling and tapping for screws would look nice.



Acumath Flat Spring
- I have used Acumath cursor springs that are found on almost all of their models, to repair missing Pickett Microline plastic series cursor springs. I also use this design for the 3D printed cursor blocks shown below.


Dietzgen 1759-B c1920 with c1936 K&E 4053 Cursor

Most K&E cursors will mount on the Dietzgem stocks as in the above example. Note the E(K) scale on the lower edge that needs a hairline on the cursor block.


Weber 4285-A (Charvoz-Roos SR104/105) with Sterling 587 Cursor
These WWII period slide rules have the same gr0ove dimensions as the plastic Sterling 587 Pocket Cursor. Original stock plastic cursor shown below. Also fits the Roos Company PSR-101 pocket slide rules.



Replica Lasercut Plastic Lens (Windows).

Requires adding the hairline using a hobby knife and ink.


Hemmi & Post Glass Lens Sizes 1-2-3-4-5-6

ISRM L-HP-1, L-HP-2 thru L-HP-6.


Pickett Flat Lens Sizes 1-2-3

ISRM L-PI-1, L-PI-2, L-PI-3.


Pickett Grooved Flat Lens Sizes 4-5-6-7

ISRM L-PI-4, L-PI-5, L-PI-6. L-PI-7.


Pickett Convex Lens Sizes 8-9-10

ISRM L-PI-8, L-PI-9, L-PI-10.


K&E All-glass cursor lens (pre 1936) Sizes 1-2-3-4-5

ISRM L-KE-1, L-KE-2 thru L-KE-5.


K&E Metal Framed Cursor Lenses (1936+) Sizes 6-7-8-9-10

ISRM L-KE-6, L-KE-7 thru L-KE-10.


K&E 408X/409X hybrid lens.(prototype)

ISRM L-KH-11

A replica lens resembling the flat all-glass cursor lens, but has the same hole pitch top and bottom of the 1936 wide-stock duplex metal frame cursor. Can be used to replace corroded or broken frames on existing OEM blocks or the replica K&E duplex blocks


K&E 4053/407X/408X/409X hybrid lens
.
ISRM L-KH-12, L-KH-13, L-KH-14

An updated replica lens resembling the flat all-glass cursor lens, but has the same hole pitch top and bottom of the 1936 wide-stock duplex metal frame cursor. Can be used to replace corroded or broken frames on existing OEM blocks or the replica K&E duplex blocks. it has the sides cutout to get the hairline past the index marks. 408X and 409X versions are identical.
L-KH-12 4053 STL Files
L-KH-13 407X STL Files
L-KH-14 408X STL Files


Dietzgen All-glass and Metal Framed cursor lens Sizes 1-2-3-4-5

ISRM L-DI-1, L-DI-2 thru L-DI-5.


Acu-Math Frameless plastic cursor lens.

ISRM L-AM-1



Replica 3-D printed Cursor blocks.

Requires cleaning of the pilot hole with a #53 (0.595 in dia) drill and threaded with a 1-72 UNF tap.
In some cases a new hole must be matched drilled using a lens or frame as a guide.



K&E 4053 Rev A - New Improved Cursor Block

ISRM B-KE-4053A-NIC

First Prototype. TinkerCad STL design.
Uses 2 each as the holes are identical on the top (Logo side) and bottom (Spring side). 200 available STL Files
Hole spacing for New Improved Cursor lens with metal frame


K&E 4108 Military Cursor Block Rev B and American Blueprint

ISRM B-KE-MIL

This block is similar to the K&E 4053 simplex blocks but longer. The screw pitch matches the frame of the 408X New Improved Cursor or can use the Hyprid all-glass lens with the same hole pitch top and bottom. Can be cut shorter and drilled for K&E 4053-3 NIC models. 200 available.


K&E 407X Duplex Cursor Block Rev A - AGC or NIC

ISRM B-KE-407X-AGC

Note: This prototype block was not made with pilot holes as the all-glass cursors (AGC) have different pitch between the top and bottom threaded holes, which are also different than the metal framed (NIC) models. Use the proper lens as a drill template for a #53 drill and 1-72UNF tap.200 available
Shown drilled for New Improved Cursor metal frames. NIC STL File


K&E 408X-3 New Improved Cursor Block Rev B

ISRM B-KE-408X-PROTO

First Prototype
TinkerCad STL design. 200 available. STL Files

Shown mounted on K&E 4081-3 with K&E Metal framed lens and ISRM L-KH-11 replacement


K&E 4053 All-Glass Cursor Block Hairline Side (for K scale on edge) Rev A

ISRM B-4053-AGC-K

Tinkercad STL design STL Files


K&E 4053 All-Glass Cursor Block Spring Side Rev A

ISRM B-4053-AGC-S

Tinkercad STL design STL Files


K&E 4053 New Improved Cursor Block with Hairline (for K scale on edge) Rev A

ISRM B-KE-4053-NIC-K

Tinkercad STL design STL Files



K&E 409X-5 20" All-Glass Cursor Block Rev A

ISRM B-409X-5-AGC-L

Hole spacing for All-Glass Cursor lens. Use for bottom (logo side)

Solidworks STL design STL Files


K&E 409X-5 20" All-Glass Cursor Block Rev A

ISRM B-409X-5-AGC-S

Hole spacing for All-Glass Cursor lens. Use for top (spring side)

Solidworks STL design STL Files


K&E 408X-5 20" New Improved Cursor Block Rev A

ISRM B-408X-5-NIC-L

Hole spacing for metal framed lens. Use for both sides.

Solidworks STL design STL Files


K&E 408X-3 New Improved Cursor Block Rev C

ISRM B-408X-NIC

Hole spacing for New Improved Cursor lens with metal frame. Use for top (spring side) and bottom (logo side)

Solidworks STL design STL Files

Replacement Screws.



Screw 1-72 UNF x 0.125in For K&E NIC Cursors.

McMaster Carr 91792A063 18-8 Stainless Steel Pan Head Slotted Screws
For replacing screws on New Improved Cursor metal frames lens (8 per)


Screw 1-72 UNF x 0.188in For K&E AGC Cursors.

McMaster Carr 91792A065 18-8 Stainless Steel Pan Head Slotted Screws
For replacing screws on All-Glass lens (8 per). Required for ISRM replica laser-cut lens.


Screw 3-48 UNC 0.188in For Pickett End Braces.

McMaster Carr 91793A091 Stainless Steel Binding Head Slotted Screws
For replacing Pickett screws that are used on the end braces (2 per)


Screw M2 x 2.4mm For Pickett Nylon Cursors.

McMaster Carr 99461A918 18-8 Stainless Steel Threadforming For Plastic, Phillip Head Screws
For replacing Pickett screws that mount the flat and convex lens to the cursor blocks.(6 per)

Cursor Springs and Retainers.



Pocket Watch MainSprings 16 Size. (2.8 mm wide)

Vintage New Old Stock mainsprings are available on ebay.

The "Size" refers to the case size or style of the pocket watch, not the dimensions of the mainspring inside.
Pocket Watch Sizes


Annealing the mainsprings.

To form a tempered spring you need to anneal (soften the spring steel, by heating the metal past cherry red and and allow it to cool slowly, in order to remove internal stresses.

Unwind the spring straight with two pairs of pliers so you don't burn yourself, and run it slowly through a flame. My kitchen stove is handy. The annealed metal will now stay straight.


Drilling and Forming Spring.

The annealed flat spring can be drilled with a quality drill bit and formed with needle-nose pliers.

The Spring can be cut with a pair of scissors, formed, and in this case. an 0-80 screw was used as a retaining pin. It was pressed in with pliers.


Captive Fastening Pin for replica Cursors.

McMaster Carr 90367A114 PEM Fastener TK4-10-250 18-8 Stainless Steel Captive Fastening Pins for Soft Materials.

I used this teeny pin with a low profile head for attaching a replica flat spring to a cursor block. It needs a press fit. Drill a 0.051" hole in the spring and a 0.039" hole in the cursor block.

Demonstration Slide Rule Cursors.


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International Slide Rule Museum