Hole End Clock Mainspring

$10.00$40.00

Hole end clock mainsprings

Please see information tabs to learn how to get the correct hole end clock mainspring. A hole-end clock mainspring is they type of spring that is enclosed in a barrel cover.

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HEMSP: $10.00$40.00
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.

Let us do it instead

Offering a mainspring replacement service, send us the entire barrel. We will use special tools to safely remove the spring and measure it, and we will swap it out for the new one. Measuring Hole End Mainsprings includes these things, the thickness, the length and also the width. We will match it up with the chart to get the new one installed. If sending the barrel please leave the mainspring in the barrel and do not remove it. This is because we need to know what way the clock mainspring gets wound inside the barrel in order to replicate this with the new one.

Measuring Hole End Mainsprings

Measuring is done to get the size of the new mainspring to match up to the old one. The width is measured first and matched up to the width below, then the thickness is measured with a micrometer, then the approximate length.

Width

Width of Hole End Mainsprings is done first. This can be measured in inches or millimeter with a digital micrometer. Then see what spring is closest in thickness and length that will be closest to the old one.

Thickness

The width of the clock spring written down and the section of the chart located at this point. The width of Hole End Mainsprings is done next. This can be measured in inches or millimeter with a digital micrometer. Then see what spring is closest in length that will be closest to the old one.

Length

The length measuring can be the hardest part of this. Close enough is sufficient for this if the spring is way too short it only means the clock will not run 8 days. It is not easy to uncoil this spring to get the length. What we end up doing is putting one end in a vise and stretching it out with a tape measure. Of course when you let go it snaps back quickly and wildly.

Diameter

This is just the width of the inside of the clock barrel. As we said the barrel is what houses the Hole End Mainsprings. Barrel inside diameter is listed because it can help know what the spring is supposed to fit into that space.

Measuring a Hole End Mainspring

If there is no match

Sometimes there just is no match for a mainspring and it is required to use a size that is not the same. Its a tough choice at times what to substitute with in this situation. As far as the width goes its best to go skinnier one instead of wider. The spring that is too wide will make the barrel cap not go on, or stay on. The thickness is pretty important to hopefully get right. If it is too thick it will put up a fight getting in the barrel and may not want to go in. If it is too thin it may not run the clock. The length is the duration the clock will run such as 8 days or less if its too short.

Measuring the Clock Mainspring
Measuring the Clock Mainspring
Measuring the Clock Mainspring
Measuring the Clock Mainspring
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.

Get a new movement instead

A movement that is 25-30 years old has lived its life. Subsequently, a new movement would be the best thing at this point because of the cost and time it would take to make it right.

If you would like to explore the new movement option rather than replacing the mainspring, please provide the movement numbers off of the back plate of the movement itself and email this information to us. There is another option also, send the clock mainspring barrel and we will swap it out with the correct new mainspring for a fee.

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 NumberMainspring Dimensions MM
1017 x .45 x 1490
1117 x .42 x 1500
20 & 5617 x .38 x 1200
21 & 5017 x .40 x 1200
3112 x .34 x 1150
3212 x .42 x 1100
3312 x .32 x 1150
4017 x .38 x 1100
4121 x .40 x 1550
4217 x .40 x 1100
5217 x .42 x 1200
5421 x .42 x 1900
5521 x .45 x 1800
The content of this website is copyright by Clockworks and written by James Stoudenmire

Hole End Clock Mainspring

The width is measured first and matched up to the width below, then the thickness is measured with a micrometer, then the approximate length. Choose the item number of that mainspring from the order list of options and push the add to cart button.


Measurements to Item #

WIDTH inch | mmTHICKNESS inch | mmLENGTH inchDIAMETER mmItem #
3/32" | 2.3.007" | 0.1818"14CMH 100
5/32" 4.008" | 0.224"17CMH 101
5/32" 4.011" | 0.2826 1/2"22CMH 103
3/16" 4.8.009" | 0.2324"17CMH 104
7/32" 5.6.008" | 0.226"20CMH 105
7/32" 5.6.0095" 0.2424"18CMH 106
1/4" 6.4.011" 0.2815 3/4"MBCMH 109
1/4" 6.4.011" 0.2839"26CMH 110
9/32 7.007" 0.1844"19CMH 111
9/32 7.010" 0.2518"MBCMH 112
9/32" 7.010" 0.2539 1/2"25CMH 113
5/16" 8.008" 0.227"18CMH 114
5/16" 8.010" | 0.2528"19CMH 116
5/16" 8.010" | 0.2532"23CMH 117
5/16" 8.010" | 0.2539 1/2"25CMH 118
5/16" 8.011" | 0.2845 1/4"28CMH 119
5/16" 8.015" 0.3840"34CMH 120
5/16" 8.016" 0.4154"38CMH 121
11/32" 8.7.013" 0.3366"38CMH 122
23/64" 9.011" 0.2845 1/4"28CMH 124
23/64 9.0125" 0.3218 1/2"MBCMH 125
3/8 9.5.011" 0.2848"26CMH 126
3/8" 9.5.014" 0.3648"32CMH 127
3/8" 9.5.017" 0.4354"38CMH 128
25/64" 10.011" 0.2845 1/4"28CMH 130
25/64" 10.012" | 0.3273"40CMH 131
7/16" 11.010" | 0.2532 1/4"22CMH 132
7/12" 11.011" | 0.2849"28CMH 135
7/16" 11.0155" | 0.455 1/2"38CMH 136
15/32" 12.010" | 0.2539 1/2"25CMH 137
15/32" 12.012" 0.353"32CMH 139
15/32" 12.014" 0.3672"41CMH 140
15/32" 12.013" 0.3327"25CMH 141
1/2" 12.7.013" 3360"36CMH 142
1/2 12.7.015" 0.3836"25CMH 143
1/2 12.7.016" 0.4165"32CMH 144
1/2" 12.7.018" 0.4660"38CMH 145
33/64" 13.010" 0.2539 1/2"25CMH 146
33/64" 13.010" 0.2845 1/2"28CMH 147
33/64".012" | 0.353"32CMH 148
33/64" 13.014" | 0.3638"30HCMH 150
33/64" 13.022" | 0.5528"32HCMH 151
17/32" 13.5.010" | 0.2672"34CMH 149
35/64" 14.011" | 0.2845 1/4"28CMH 152
35/64" 14.011" 0.2849"30CMH 153
35/64" 14.012" 0.361"35CMH 155
35/64" 14.0155" 0.437 1/2"36CMH 156
9/16" 14.3.012" 0.339"28CMH 157
35/64 14.013" 0.3327"25CMH 158
35/64 14.014" 0.3632"30CMH 159
9/16" 14.3.015" 0.3842"28CMH 160
19/32" 15.011" 0.2845 1/4"28CMH 161
19/32" 15.011" | 0.2849"30CMH 162
19/32" 15.012" | 0.353"32CMH 163
5/8" 16.010" | 0.2539 1/2"25CMH 164
5/8" 16.011" | 0.2845 1/4"28CMH 165
5/8" 16.011" | 0.2849"30CMH 166
5/8" 16.013" 0.3378"34CMH 167
5/8" 16.013" 0.33105"47CMH 168
5/8" 16.014" 0.3670"39CMH 169
5/8" 16.016" 0.4159"35CMH 170
5/8 16.0175" 0.4543 1/2"37CMH 171
5/8 16.018" 0.4641"36CMH 172
5/8" 16.018" 0.4672"40CMH 173
5/8" 16.018" 0.4696"53CMH 174
43/64" 17.010" | 0.2572"34CMH 176
43/64" 17.010" | 0.2539 1/2"25CMH 177
43/64" 17.011" | 0.2845 1/4"28CMH 178
43/64" 17.011" | 0.2849"30CMH 179
43/64" 17.018" | 0.4654"40CMH 180
11/16" 17.5.012" 0.372"30CMH 181
11/16" 17.5.014" 0.3654"34CMH 182
45/64" 18.018" | 0.4644"38CMH 183
11/16" 17.5.018" 0.4696"53CMH 184
45/64" 18.011" 0.2845 1/4"28CMH 185
45/64 18.011" 0.2849"30CMH 186
45/64 18.012" 0.353"32CMH 187
45/64" 18.012" 0.361"35CMH 188
45/64" 18.016" 0.4156"39CMH 189
45/64" 18.016" 0.4161 1/2"42CMH 190
45/64" 18.0175" | 0.4470"45CMH 191
45/64" 18.019" | 0.4847"35CMH 192
45/64" 18.021" | 0.5348"40CMH 193
3/4" 19.009" | 0.2372"33CMH 194
3/4" 19.010" 0.2539 1/2"25CMH 195
3/4" 19.011" 0.2845 1/4"28CMH 196
3/4" 19.011" 0.2849"30CMH 197
3/4" 19.011" 0.2850"30CMH 198
3/4 19.012" 0.353"32CMH 199
3/4 19.012" 0.361"35CMH 200
3/4" 19.012" 0.375"35CMH 201
3/4".012" 0.390"35CMH 202
3/4" 19.014" | 0.3690"35CMH 204
3/4" 19.015" | 0.3872"36CMH 205
3/4" 19.0155" | 0.453 1/2"37CMH 206
3/4" 19.016" 0.4153"38CMH 208
3/4" 19.016" 0.4156"39CMH 209
3/4" 19.016" 0.4160"38CMH 210
3/4" 19.017" 0.4344"35CMH 211
3/4 19.017" 0.4345"36CMH 212
3/4 19.0175" 0.4470"45CMH 213
3/4" 19.018" 0.4696"53CMH 214
3/4" 19.019" 0.4868 1/2"45CMH 215
25/32" 20.011" | 0.2849"30CMH 217
25/32" 20.012" | 0.353"32CMH 218
25/32" 20.012" | 0.361"35CMH 219
25/32" 20.0155" | 0.453"38CMH 220
25/32" 20.016" | 0.4153"38CMH 221
25/32" 20.0175" 0.4470"45CMH 222
25/32" 20.018" 0.4676 1/2"48CMH 223
53/64" 21.011" 0.2845 1/4"28CMH 224
53/64" 21.011" 0.2849"30CMH 225
53/64 21.012" 0.353"32CMH 226
53/64 21.012" 0.361"35CMH 227
53/64" 21.0125" 0.3267"38CMH 228
53/64" 21.015" 0.38100"50CMH 229
7/8" 22.2.011" 0.2849"30CMH 230
7/8" 22.2.012" | 0.353"32CMH 231
7/8" 22.2.012" | 0.361"35CMH 232
7/8" 22.2.0125" | 0.3267"38CMH 233
7/8" 22.2.013" | 0.3372"33CMH 234
7/8" 22.2.0155" | 0.450"37CMH 235
7/8" 22.2.0175" 0.4470"45CMH 236
7/8" 22.2.018" 0.4684"49CMH 237
7/8" 22.2.018" 0.4696"53CMH 228
7/8" 22.2.0195" 0.556"42CMH 239
61/64 24.0175" 0.4470"45CMH 240
61/64 24.018" 0.4676 1/2"48CMH 241
61/64" 24.018" 0.4680 1/2"50CMH 242
63/64" 25.018" 0.4678 1/2"49CMH 243
1" 25.4.018" 0.4696"53CMH 244

Additional information

Weight0.2 lbs
Mainspring

CMH 101, CMH 100, CMH 103, CMH 104, CMH 105, CMH 106, CMH 109, CMH 110, CMH 111, CMH 112, CMH 113, CMH 114, CMH 115, CMH 116, CMH 117, CMH 118, CMH 119, CMH 120, CMH 121, CMH 122, CMH 123, CMH 124, CMH 125, CMH 126, CMH 127, CMH 128, CMH 130, CMH 131, CMH 132, CMH 135, CMH 136, CMH 137, CMH 139, CMH 140, CMH 141, CMH 142, CMH 143, CMH 144, CMH 145, CMH 146, CMH 147, CMH 148, CMH 149, CMH 150, CMH 151, CMH 152, CMH 153, CMH 155, CMH 156, CMH 157, CMH 158, CMH 159, CMH 160, CMH 161, CMH 162, CMH 163, CMH 164, CMH 165, CMH 166, CMH 167, CMH 168, CMH 169, CMH 170, CMH 171, CMH 172, CMH 173, CMH 174, CMH 176, CMH 177, CMH 178, CMH 179, CMH 180, CMH 181, CMH 182, CMH 183, CMH 184, CMH 185, CMH 186, CMH 187, CMH 188, CMH 189, CMH 190, CMH 191, CMH 192, CMH 193, CMH 194, CMH 195, CMH 196, CMH 197, CMH 198, CMH 199, CMH 201, CMH 202, CMH 204, CMH 205, CMH 206, CMH 208, CMH 209, CMH 210, CMH 211, CMH 212, CMH 213, CMH 214, CMH 215, CMH 216, CMH 217, CMH 218, CMH 220, CMH 221, CMH 222, CMH 223, CMH 224, CMH 225, CMH 226, CMH 227, CMH 228, CMH 229, CMH 230, CMH 231, CMH 232, CMH 233, CMH 234, CMH 235, CMH 236, CMH 237, CMH 238, CMH 239, CMH 240, CMH 241, CMH 242, CMH 243, CMH 244

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