How to drill mounting holes trough an iron transformer core? - Page 1
Forum section: electronics / beginners

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: October 20, 2022, 09:08:39 am
content: how do I do this right? I have a transformer that has a mounting bracket to mount it on it's side, but I need to mount it on it's belly.the most logical way to do this would be to drill holes trough the edges of the core, but how do I do this without shorting them all to each other, or does that not matter if it's just on 4 places?I think the layers have all shorted anyway, the core is pretty loose, buzzes a ton, and the transformer heats up a lot even if no current is drawn from the secondaries.

author: jpanhalt
author_rank: Super Contributor
timestamp: October 20, 2022, 09:33:05 am
content: How about a picture? From a bracket on the side, you could use a right angle bracket(s) to mount it at 90°. There are probably other solutions that do not involve making new holes.

author: DavidKo
author_rank: Frequent Contributor
timestamp: October 20, 2022, 09:39:03 am
content: Silicon steel is hard to drill. The shape is usually done by stamping.

author: HighVoltage
author_rank: Super Contributor
timestamp: October 20, 2022, 09:42:52 am
content: Transformer steel is very difficult to drill.But with an very good drill bit this is possible and can be done.

author: pcprogrammer
author_rank: Super Contributor
timestamp: October 20, 2022, 09:48:06 am
content: There is also the risk of deforming the slats, when the drill makes it through the first one and then pulls it up, and then the next one, etc.Need to clamp it in very well.

author: jpanhalt
author_rank: Super Contributor
timestamp: October 20, 2022, 10:20:54 am
content: It seems designed for mounting with a bracket(s) with laminations perpendicular to the mounting surface. Any edge can be made "down." I would use a pair of brackets -- one on each face of the laminations. If you want the coil facing the mounting surface, then I would use solid standoffs, e.g., bar or extrusion to fill the gap between the face of the laminations and mounting surface.EDIT: This describes and provides images of various styles of mounting that I tried to describe:https://www.mercurymagnetics.com/what-you-need-to-know-about-transformer-mounting-styles/

author: Ian.M
author_rank: Super Contributor
timestamp: October 20, 2022, 10:28:05 am
content: For a heavy transformer of the style shown, I'd go with clamping bars above and below parallel to and bearing on the outer limbs of the core, held together by four allthread studs through holes in their ends. The studs should not touch the core (or if they do, insulate them with rubber tubing) and the bars should be insulated from the core with rubber or foam sheet to damp vibration and avoid introducing any new eddy current paths. Probably the easiest would be to stick the bars to the core with 3M VHB tape or similar. The studs would protrude downwards through spacers to keep the bobbin from being crushed against the chassis and the whole assembly would be secured by nuts on the studs under the chassis.

author: Infraviolet
author_rank: Super Contributor
timestamp: October 21, 2022, 01:34:00 am
content: Could you just 3d print or otherwise manufacture a closely fitting cage of non-conductive material to go around the transformer with mounting holes where you actually want them? Hold the transformer in to the cage by the fit of the cage around it, rather than by mounting holes through it? A chopepd up project box, perhaps one slightly too small on one axis so when you tighten down the box's lid with corner screws that tightly holds the transformer?

author: EPAIII
author_rank: Super Contributor
timestamp: October 21, 2022, 08:29:20 am
content: It would bend any bracket??? Not so. The bracket just must be made of a sufficient gauge of steel or other material.I also have a machine shop and can attest to the hardness of the alloys used for transformers. While it is not impossible to drill, I would want a solid carbide drill bit and would hold it in a milling vise in my milling machine to do that job. I guess it could be done with a drill press if you used a good vise and clamped it down to the table, but the milling machine would be my choice.A local machine shop or junk yard may be a good source for a short length of heavy-duty steel or aluminum angle for a bracket. I am thinking about one of about 2" (50mm) or 3" (75mm) size. You should be able to cut it to length and drill holes in it with hand tools a lot easier than drilling holes in the transformer.Quote from: ELS122 on October 20, 2022, 09:55:40 am

author: jonpaul
author_rank: Super Contributor
timestamp: October 21, 2022, 06:56:25 pm
content: BonjourMost lams have prepunched holes for long screws to close the stack.Drilling creates burrs that ruin the lam stackEI/EE/UI standard laminations have clamps or brackets that grip the edges of the lam stack.Jon

author: Jeroen3
author_rank: Super Contributor
timestamp: October 21, 2022, 09:16:19 pm
content: You should not drill the laminated steel sheets. It creates a short circuit and excess heating.Instead, you should mount the transformer using it's intended mounting holes. Using a custom made bent steel bracket if you have to.Having a bracket custom made doesn't have to be very expensive. Draw some up in fusion360 and find a steel shop near you. Should be possible under 100 EUR. Or DIY with some mild steel.