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.
First, measure the Hole End Mainspring by taking the spring out of the brass clock movement barrel.
Then 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. Of course, it can whack, cut and may even shatter, into pieces. So, 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.
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 Damage
When a clock mainspring breaks the impact can cause damage to the movement. This 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. So it is 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.
When a mainspring breaks, the barrel and the next wheel up gets the most impact and is where most of the damage occurs. If there is damage to the movement that is, sometimes there is no damage at all.
Then the next thing to do is to 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
Of course, 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.
However, there is another option. If you send the clock mainspring barrel to us we will swap it out with the correct new mainspring for a fee.
Hole-End Clock Mainspring replacement-service
For a Hole-End Clock Mainspring replacement-service, all you have to do is send clockworks the clock barrel. Once we have the barrel, the old spring will be taken out. Then it is just a matter of installing the new mainspring. When sending in the mainspring, be please sure to leave the Hole-End clock mainspring within that barrel. The price for this service is $100 and it includes the cost of the Hole-End mainspring, as well as the shipping to return the barrel and new spring back to you.What will be done
Clockworks.com will remove the broken, or worn, spring from the container in a safe way. The next step is to measure the thickness and width of the spring. The final measurement requires stretching out the old spring in order to get the length. Next we will use the mainspring chart for reference so that the correct spring will be put into the barrel. 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 a special tool known as mainspring winder. Once the new spring is safely within the barrel, the cap snaps back into place and the mainspring is then on its way back to you.Removing a clock mainspring barrel
Often a clock mainspring barrel can be taken out without disassembling the clock movements outer plates, on Hermle or Kieninger clock movements. The mainspring will also still stay inside 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 comes out, you can see the number that is on the barrel end cap.
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.
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 |
Hole End Clock Mainspring
Measure the width first and match it up to the width below, then measure the thickness with a micrometer, and finally measure 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" 19.0 | .016" 0.41 | 38" | 32H | CMH 207 |
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 |
5/8" 16.0 | .024" 0.60 | 108" | - | CMH 308 |
I have a very old Seth Thomas ships bell clock that has to be wound every day. Is it possible to make it an 8 day clock by replacing the mainspring and bell spring with longer ones?
No, not in the same movement, does not work that way
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com
I thought that might be the case. I’ll have to keep it for myself and find another for a memorial to a dear Navy bud. Thanks.
Hello, I looking for replacement spring for a Silesia P24, the spring is 19mm wide, the thickness is 0.6mm, don’t know the length, the spring barrel has a diameter of 55mm. Using your chart it seems CMH 215 is the correct or at least closest option that might work. Any help is appreciated. Regards, Chuck
Yes sometimes need to get one close as you can and hope for the best. If its too short it will not run 8 full days is all. If its too long it wont go in the barrel or not easy anyway
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com
1881 -1885 E. Ingraham ‘Adrian’ model shelf clock spring. Do you have this model? or can you replace the mainspring? Do I just send in the clockworks whole? without the body of the clock?
Hi,
Sorry to say that one is no longer available new. We can overhaul this one if you like, we only need the movement alone sent in. We can tell you how to remove it and reinstall it, help you along the way. When its done and installed it will run for years.
We start with this =
CLEANING AND OILING FOR ONLY $200
We have the best and most expensive tooling, cleaning equipment, and cleaning solutions. There is no expense spared by us when it comes to having the best equipment. With this factor and 3 generations of clock repair expertise, you can rest assured your clock works will be in the best hands it can be in.
For this unit, we will take the movement in, unpack it, and then clean it and inspect it for $200. If it passes inspection, we will oil it and test it. If this is all that is needed that is all it will cost is the $200 plus the shipping back to you. The initial $200 is non refundable and is the fee for the cleaning, inspection, and oiling and testing only. We do need to be paid for our time on this even if the clock movement is deemed unrepairable for some reason.
Please let us know if you are interested in this service by filling out the repair form at this link, https://www.clockworks.com/clock-repair-service.html because it would be an absolute pleasure to get this one shiny and working again.
Thank you !
Clockworks Team
I’m looking for two springs that are 0.75 x .27 x 96”. Holes at each end. Do you have those available?
Hi,
We have these hole end clock mainsprings available
https://www.clockworks.com/product/hole-end-clock-mainspring
James
Do these springs have holes at both ends?
Hi,
Yes they do
https://www.clockworks.com/product/hole-end-clock-mainspring
James
I’m looking for a clock mainspring, hole end, 28.15 mm wide, .35 mm thick 2082. 8 mm long or something close.
We have these to offer
https://www.clockworks.com/product/loop-end-clock-mainspring
James
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]
Yes best to bring that one to the repair shop. I really just do not know the answer from here.
Many Thanks !
James and Donna Stoudenmire http://www.clockworks.com 124 Goss Hill = UPS Mailing PO Box 339 = USPS Mailing Huntington, MA 01050 USA clockworks@clockworks.com
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