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
SKU: HEMSP Categories: , , Tags: ,
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 wound in a brass barrel enclosure is known as a Hole End Mainspring. Measure the Hole End Mainspring by taking the spring out of the brass clock movement barrel. The mainspring has to come out of the brass barrel in order to measure it. There is no other way to do this task. This sounds easy but carefully read the following text on how to do this safely.

Warning

WARNING: Always wear safety glasses and gloves when working with hole end mainsprings. They can, and will be, extremely dangerous to work on. Removal can be violent so please be cautious and know that springs always store power when it is in a coil for so long. The spring can be broken, or off the hook from the center, and still have an extreme amount of power in the spring. It can whack, cut and may even shatter, into pieces. Severe damage to fingers and eyes is a real possibility so protective gear is mandatory.

Let us do it instead

Clockworks offers a mainspring replacement service so send us the entire barrel and avoid the hassle altogether. We will use special tools to safely remove the spring, measure it, and swap it out for the new one. Measuring Hole End Mainsprings includes the thickness, the length and also the width. Then a comparison of these measurements to the mainspring chart will show the appropriate spring to install. If sending in the barrel, please leave the mainspring in the barrel. Do not remove it. This is because we need to know which way the clock mainspring gets wound inside the barrel. If the spring is out of the barrel the direction will not be known. Of course this is important in order to replicate the same direction 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. Measure the width first, then measure the thickness with a micrometer. Then the final measurement is the approximate length. Take all those numbers and compare them to the chart.

Width

Width of Hole End Mainsprings is done first. Measure this in inches or millimeters with a digital micrometer. Then see which spring matches the best in width to the old one.

Thickness

Once the width of the clock spring is written down and you are in the right location of the chart, continue with the next measurement. The thickness of the Hole End Mainspring is done next. This measurement can be in inches or millimeters with a digital micrometer. Take this measurement and compare it to the chart along with the width measurement. Then see which spring comes closest to the old spring.

Length

Measuring the length 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 for 8 days. So more frequent winding will need to be done. 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 before, the barrel is what houses the Hole End Mainsprings. The barrel inside diameter is in the list because it can help determine the size of the spring that can fit into that space.

Measuring a Hole End Mainspring

If there is no match for the Hole end Mainspring

Sometimes there just is no match for a mainspring and another size has to be put in. It's a tough choice at times what to substitute with in this situation. As far as the width goes it's best to go with a 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 it's too short.

Clock Mainspring
Clock Mainspring
Measuring the Clock Mainspring
Measuring the Clock Mainspring
The content of this website is copyright by Clockworks and written by James Stoudenmire in year 2020

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 in year 2020

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 in year 2020

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 the control the speed of the unwind with the 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. 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 in year 2020

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 in year 2020

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 | 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
9/16" 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

Additional information

Weight 0.2 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 219, 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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Linda Sylvestser
Linda Sylvestser
10 months ago

I am looking for a 1/4 inch hole end wide ribbon spring to replace a broken one in a vintage doll (Tiny Thumbelina, the mechanism makes the head move). I have done a lot of research and believe it or not there is very little out there and I cannot find a replacement. This is the closest I have found. Do you think a CHM 109 might be appropriate for this replacement? I was thinking I might be able to take the mechanism to a clock repair shop with the new spring to see if they could replace the mainspring.
Please let me know what you think.
Thank you.
Linda Sylvester
[email protected]

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