Clock Movement Hole-End Mainsprings

Hole End Clock Mainspring - For a mechanical spring driven clock movements that have a barrel cover over the spring. - Clockworks
MainspringsMeasuring the MainspringAssessment of damageReplacement serviceRemoving a barrelHermle barrel numbers

Please view these information tabs to help with the proper Clock Movement Hole-End Mainsprings size for your clock.

About Hole End Mainsprings

The type of springs that are contained in a brass barrel enclosure is known as Hole End Mainsprings. Measuring Hole End Mainsprings is done with the spring out of the clock movement brass barrel. The mainspring has to come out of the brass barrel to measure it.

Warning

WARNING: Wear safety glasses and gloves if working with a hole end mainsprings, they can and will be dangerous. Removal can be violent please be cautious and know there is stored power in any coiled up spring. The spring can be broken or unhooked from the center and still have much power in that spring. It can wack, cut and it may even shatter into pieces.

The content of this website is copyright by Clockworks and written by James Stoudenmire

Clock Mainspring Damage

When a clock mainspring breaks the impact can cause damage to the movement. Damage would be within the parts of the gear train itself. It is possible that the pivots that go into the outer plates or the arbors have bent. Best to check the clock movement's condition before ordering a clock mainspring.

What to check

If working with a hole end clock mainspring it's best to check the teeth on the barrel for damage. A barrel is a container that covers the mainspring on some clocks. The barrel and the next wheel up gets the most impact and is where most of the damage would be. If there is damage to the movement that is, sometimes there is no damage at all. Then check the arbor on the next wheel up since it gets bent often when the mainspring breaks. Another option is to send it in for a movement restoration. Clockworks will clean, oil, re-bush, repair and test the unit doing a full movement restoration job.

The content of this website is copyright by Clockworks and written by James Stoudenmire

Hole-End Clock Mainspring replacement service

For a hole-end clock mainspring replacement, send clockworks the clock barrel and we will swap out the mainspring. Leave the Hole-End clock mainspring within that barrel. The price for this service is $80 and includes the cost of the Hole-End mainspring and shipping back.

What will be done

clockworks.com will remove the broken or worn spring from the container in a safe way. Then measuring the thickness and width and stretching it out to get the length. Next we will use the chart to get the right one from the list. We will then pull that spring from the inventory that is already here with us at Clockworks. The installation of the spring will be done with the special tool called a mainspring winder.

The content of this website is copyright by Clockworks and written by James Stoudenmire

Removing a clock mainspring barrel

Often a clock mainspring barrel can be removed without disassembling the clock movements outer plates. The mainspring will also still be contained within the barrel.

Letting down the mainspring power

The mainspring let down tool allows the release of the mainspring with the fist rather than the fingers. Put the mainspring let down tool over the square post the key goes onto. With a flat screwdriver, move the click out of the way. The click has a tension spring that needs to be held back. This is what holds the mainspring so that it winds in only one direction. Slowly allow the mainspring to unwind in the fist. This method lets you control the speed of the unwind with your whole fist rather than the fingers. Unquestionably, doing this with a key will result in a painful experience on the fingers. Of course, if the mainspring is broken, there usually is no worry since there isn't much tension to begin with.

After the barrel is out

Once the power has been let down, the next step is to yank out the winding arbor shaft. The clock mainspring barrel should then fall out the side of the movement. After the barrel is removed, it can be seen the number that is on the barrel end cap. This will tell what hole end mainspring to order. You can locate the mainspring by using the hole end mainspring chart. Be sure to check the movement for any damage as a result of the mainspring breaking. In particular, inspect the teeth of the gears, as well as the arbor on the next wheel up. This could have consequently been bent.

The content of this website is copyright by Clockworks and written by James Stoudenmire

Hermle mainspring barrel numbers

Hermle mainspring barrel numbers

Mainspring barrel number to size spring

Barrel Number Mainspring Dimensions MM
10 17 x .45 x 1490
11 17 x .42 x 1500
20 & 56 17 x .38 x 1200
21 & 50 17 x .40 x 1200
31 12 x .34 x 1150
32 12 x .42 x 1100
33 12 x .32 x 1150
40 17 x .38 x 1100
41 21 x .40 x 1550
42 17 x .40 x 1100
52 17 x .42 x 1200
54 21 x .42 x 1900
55 21 x .45 x 1800
The content of this website is copyright by Clockworks and written by James Stoudenmire

Instructions

The width is measured first and matched up to the width below. Next is the thickness is measured with a micrometer. Lastly the approximate length. MB stands for Music Box, and H stands for Horolovar. Please select View Product to see the list of mainsprings we have to offer and the prices.

HEMSP: $10.00$40.00
View Product

Hole End Mainsprings Measurements to item #
WIDTH inch | mm THICKNESS inch | mm LENGTH inch DIAMETER mm Item #
3/32" | 2.3 .007" | 0.18 18" 14 CMH 100
5/32" 4 .008" | 0.2 24" 17 CMH 101
5/32" 4 .011" | 0.28 26 1/2" 22 CMH 103
3/16" 4.8 .009" | 0.23 24" 17 CMH 104
7/32" 5.6 .008" | 0.2 26" 20 CMH 105
7/32" 5.6 .0095" 0.24 24" 18 CMH 106
1/4" 6.4 .011" 0.28 15 3/4" MB CMH 109
1/4" 6.4 .011" 0.28 39" 26 CMH 110
9/32 7 .007" 0.18 44" 19 CMH 111
9/32 7 .010" 0.25 18" MB CMH 112
9/32" 7 .010" 0.25 39 1/2" 25 CMH 113
5/16" 8 .008" 0.2 27" 18 CMH 114
5/16" 8 .010" | 0.25 28" 19 CMH 116
5/16" 8 .010" | 0.25 32" 23 CMH 117
5/16" 8 .010" | 0.25 39 1/2" 25 CMH 118
5/16" 8 .011" | 0.28 45 1/4" 28 CMH 119
5/16" 8 .015" 0.38 40" 34 CMH 120
5/16" 8 .016" 0.41 54" 38 CMH 121
11/32" 8.7 .013" 0.33 66" 38 CMH 122
23/64" 9 .011" 0.28 45 1/4" 28 CMH 124
23/64 9 .0125" 0.32 18 1/2" MB CMH 125
3/8 9.5 .011" 0.28 48" 26 CMH 126
3/8" 9.5 .014" 0.36 48" 32 CMH 127
3/8" 9.5 .017" 0.43 54" 38 CMH 128
25/64" 10 .011" 0.28 45 1/4" 28 CMH 130
25/64" 10 .012" | 0.32 73" 40 CMH 131
7/16" 11 .010" | 0.25 32 1/4" 22 CMH 132
7/12" 11 .011" | 0.28 49" 28 CMH 135
7/16" 11 .0155" | 0.4 55 1/2" 38 CMH 136
15/32" 12 .010" | 0.25 39 1/2" 25 CMH 137
15/32" 12 .012" 0.3 53" 32 CMH 139
15/32" 12 .014" 0.36 72" 41 CMH 140
15/32" 12 .013" 0.33 27" 25 CMH 141
1/2" 12.7 .013" 33 60" 36 CMH 142
1/2 12.7 .015" 0.38 36" 25 CMH 143
1/2 12.7 .016" 0.41 65" 32 CMH 144
1/2" 12.7 .018" 0.46 60" 38 CMH 145
33/64" 13 .010" 0.25 39 1/2" 25 CMH 146
33/64" 13 .010" 0.28 45 1/2" 28 CMH 147
33/64" .012" | 0.3 53" 32 CMH 148
33/64" 13 .014" | 0.36 38" 30H CMH 150
33/64" 13 .022" | 0.55 28" 32H CMH 151
17/32" 13.5 .010" | 0.26 72" 34 CMH 149
35/64" 14 .011" | 0.28 45 1/4" 28 CMH 152
35/64" 14 .011" 0.28 49" 30 CMH 153
35/64" 14 .012" 0.3 61" 35 CMH 155
35/64" 14 .0155" 0.4 37 1/2" 36 CMH 156
9/16" 14.3 .012" 0.3 39" 28 CMH 157
35/64 14 .013" 0.33 27" 25 CMH 158
35/64 14 .014" 0.36 32" 30 CMH 159
9/16" 14.3 .015" 0.38 42" 28 CMH 160
19/32" 15 .011" 0.28 45 1/4" 28 CMH 161
19/32" 15 .011" | 0.28 49" 30 CMH 162
19/32" 15 .012" | 0.3 53" 32 CMH 163
5/8" 16 .010" | 0.25 39 1/2" 25 CMH 164
5/8" 16 .011" | 0.28 45 1/4" 28 CMH 165
5/8" 16 .011" | 0.28 49" 30 CMH 166
5/8" 16 .013" 0.33 78" 34 CMH 167
5/8" 16 .013" 0.33 105" 47 CMH 168
5/8" 16 .014" 0.36 70" 39 CMH 169
5/8" 16 .016" 0.41 59" 35 CMH 170
5/8 16 .0175" 0.45 43 1/2" 37 CMH 171
5/8 16 .018" 0.46 41" 36 CMH 172
5/8" 16 .018" 0.46 72" 40 CMH 173
5/8" 16 .018" 0.46 96" 53 CMH 174
43/64" 17 .010" | 0.25 72" 34 CMH 176
43/64" 17 .010" | 0.25 39 1/2" 25 CMH 177
43/64" 17 .011" | 0.28 45 1/4" 28 CMH 178
43/64" 17 .011" | 0.28 49" 30 CMH 179
43/64" 17 .018" | 0.46 54" 40 CMH 180
11/16" 17.5 .012" 0.3 72" 30 CMH 181
11/16" 17.5 .014" 0.36 54" 34 CMH 182
45/64" 18 .018" | 0.46 44" 38 CMH 183
11/16" 17.5 .018" 0.46 96" 53 CMH 184
45/64" 18 .011" 0.28 45 1/4" 28 CMH 185
45/64 18 .011" 0.28 49" 30 CMH 186
45/64 18 .012" 0.3 53" 32 CMH 187
45/64" 18 .012" 0.3 61" 35 CMH 188
45/64" 18 .016" 0.41 56" 39 CMH 189
45/64" 18 .016" 0.41 61 1/2" 42 CMH 190
45/64" 18 .0175" | 0.44 70" 45 CMH 191
45/64" 18 .019" | 0.48 47" 35 CMH 192
45/64" 18 .021" | 0.53 48" 40 CMH 193
3/4" 19 .009" | 0.23 72" 33 CMH 194
3/4" 19 .010" 0.25 39 1/2" 25 CMH 195
3/4" 19 .011" 0.28 45 1/4" 28 CMH 196
3/4" 19 .011" 0.28 49" 30 CMH 197
3/4" 19 .011" 0.28 50" 30 CMH 198
3/4 19 .012" 0.3 53" 32 CMH 199
3/4 19 .012" 0.3 61" 35 CMH 200
3/4" 19 .012" 0.3 75" 35 CMH 201
3/4" .012" 0.3 90" 35 CMH 202
3/4" 19 .014" | 0.36 90" 35 CMH 204
3/4" 19 .015" | 0.38 72" 36 CMH 205
3/4" 19 .0155" | 0.4 53 1/2" 37 CMH 206
3/4" 19 .016" 0.41 53" 38 CMH 208
3/4" 19 .016" 0.41 56" 39 CMH 209
3/4" 19 .016" 0.41 60" 38 CMH 210
3/4" 19 .017" 0.43 44" 35 CMH 211
3/4 19 .017" 0.43 45" 36 CMH 212
3/4 19 .0175" 0.44 70" 45 CMH 213
3/4" 19 .018" 0.46 96" 53 CMH 214
3/4" 19 .019" 0.48 68 1/2" 45 CMH 215
25/32" 20 .011" | 0.28 49" 30 CMH 217
25/32" 20 .012" | 0.3 53" 32 CMH 218
25/32" 20 .012" | 0.3 61" 35 CMH 219
25/32" 20 .0155" | 0.4 53" 38 CMH 220
25/32" 20 .016" | 0.41 53" 38 CMH 221
25/32" 20 .0175" 0.44 70" 45 CMH 222
25/32" 20 .018" 0.46 76 1/2" 48 CMH 223
53/64" 21 .011" 0.28 45 1/4" 28 CMH 224
53/64" 21 .011" 0.28 49" 30 CMH 225
53/64 21 .012" 0.3 53" 32 CMH 226
53/64 21 .012" 0.3 61" 35 CMH 227
53/64" 21 .0125" 0.32 67" 38 CMH 228
53/64" 21 .015" 0.38 100" 50 CMH 229
7/8" 22.2 .011" 0.28 49" 30 CMH 230
7/8" 22.2 .012" | 0.3 53" 32 CMH 231
7/8" 22.2 .012" | 0.3 61" 35 CMH 232
7/8" 22.2 .0125" | 0.32 67" 38 CMH 233
7/8" 22.2 .013" | 0.33 72" 33 CMH 234
7/8" 22.2 .0155" | 0.4 50" 37 CMH 235
7/8" 22.2 .0175" 0.44 70" 45 CMH 236
7/8" 22.2 .018" 0.46 84" 49 CMH 237
7/8" 22.2 .018" 0.46 96" 53 CMH 228
7/8" 22.2 .0195" 0.5 56" 42 CMH 239
61/64 24 .0175" 0.44 70" 45 CMH 240
61/64 24 .018" 0.46 76 1/2" 48 CMH 241
61/64" 24 .018" 0.46 80 1/2" 50 CMH 242
63/64" 25 .018" 0.46 78 1/2" 49 CMH 243
1" 25.4 .018" 0.46 96" 53 CMH 244