Clock Movement Hole-End Mainsprings

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 barrel. The mainspring has to come out of the 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 you and cut you and it may even shatter into pieces. Please use gloves and safety glasses when you work with coiled mainsprings.

Let us do it instead

If you choose, we have a mainspring replacement service, all you have to do is send us the entire barrel. When we get the 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 for you. We will ship it back the method you chose in the check out pages. If you send us 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. Be sure your cat is not sitting by the vise when you let go or it will not like you anymore.

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.

- - The content of this web page and web site was written and copyright by James Stoudenmire of Clockworks.com - It may not be used commercially without permission. - -

Clock Mainspring Damage

When a clock mainspring breaks the impact may have caused 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 mainspring.

What to check

If working with a hole end a href="/clock-parts/clock-movement-hole-end-mainsprings.html">clock mainspring its 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. The next thing to check is the arbor on the next wheel up it gets bent often when the mainspring breaks. The other option is to send it in for a movement overhaul. Clockworks.com will clean, oil, re-bush, repair and test the unit doing a full restoration job on the movement.

Get a new movement instead

If the movement is 25-30 years old, it has lived its life anyway. 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 [email protected] There is another option also, just send us the clock mainspring barrel and we will swap it out with the correct new mainspring for a fee.

- - The content of this web page and web site was written and copyright by James Stoudenmire of Clockworks.com - It may not be used commercially without permission. - -

Hole-End Clock Mainspring replacement service

Send clockworks.com the clock barrel and will swap out the spring. Leave the Hole-End clock mainspring within that barrel. The price for this service is $65 and includes the cost of the Hole-End mainspring. When added to the cart and check out online you will be charged the shipping. This shipping charge is your prepayment for the barrel to be shipped back to you.

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.com. The installation of the spring will be done with the special tool called a mainspring winder.

Sending the Hole-End mainspring

Please send the barrel with the broken Hole-End clock mainspring to us. Sent it to Clockworks.com PO Box 339 Huntington MA 01050. Please send with a copy of your receipt for the Hole-End clock mainspring replacement service. If you would like to send in your barrel with the broken mainspring, please pay at this link.

- - The content of this web page and web site was written and copyright by James Stoudenmire of Clockworks.com - It may not be used commercially without permission. - -

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

First you would use a mainspring let down tool. This device allows you to hold the tension of the mainspring with your fist rather than your 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 your fist. This method lets you control the speed of the unwind with your whole fist rather than your 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, you will be able to see the number that is on the barrel end cap. This will allow you to determine 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 web page and web site was written and copyright by James Stoudenmire of Clockworks.com - It may not be used commercially without permission. - -

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

Hermle mainspring barrel numbers

Hermle mainspring barrels have numbers on the barrel caps and therefore can be used to help identify the hole end spring contained therein. Generally speaking, these numbers sometimes can only be seen by removing the barrel from the clock because of where the number is placed on the cap, but there will certainly be a number on it. The chart provided on this page lists the various numbers found on the caps, as well as the corresponding hole end spring that will ultimately be found inside that barrel.

Check for damage

Once you have obtained the size of the hole end spring needed by the Hermle mainspring barrel number, you can therefore go ahead and find it on the hole end mainspring chart so you will be able to order a new one. Of course, if it needs a mainspring, it is quite probable that the teeth of the barrel may have been damaged when the spring broke. This is because of the incredible power of the spring. Consequently, another area that may have also gotten damaged are the teeth on the next wheel up on the train. As a result of these problems, it would be best to purchase a new movement.

Get a new movement instead

In order to identify the movement, you would first need to locate the movement number. Therefore, the back plate of the movement itself needs to be looked at. The number will be stamped right into that brass plate. Although customers sometimes think they can get the number off of the clock case, or the paperwork that came with the clock, this is not the situation. The only place that number will be is stamped into the brass. As soon as you have the numbers from the movement you can go to this page to finally find your brand new clock movement.

Another problem that occurs when the mainspring breaks is the second wheel up from the barrel gets a bent arbor. This is certainly something that needs to be checked. If the arbor did get bent, you would surely need to get a new wheel, or somehow straighten it out. Indeed, it is not always easy to get it straight, so again, sometimes it is best to just get the new unit instead.

- - The content of this web page and web site was written and copyright by James Stoudenmire of Clockworks.com - It may not be used commercially without permission. - -

Instructions

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.

Clear
HEMSP: $9.89$39.89

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