Disassembling Columbia Type N topworks

[Morell1]

Apologies if I'm breaking protocol by posting here rather than in Tips, Tricks and Tutorials. I wanted to make sure this post reached people who may have experience disassembling a Type N Graphophone top works. (I can remove this posting if it violates the rules.)

I'm trying to disassemble mine so that I can clean and properly lubricate it. I believe that would require me to remove the embossed side plate, which is apparently affixed by a number of screws and at least two pins. (See picture)..

I've removed the screws and tried gently to pry off the plate, but it won't budge, and I won't risk damaging the casting in any way. I've examined the patent drawings for this machine for clues about the topworks' construction and am none the wiser.

Does anyone have any experience in, at the very least, removing the bullet mandrel and the feed screw? I will not risk damaging the machine.

Thank you!

[ChuckA]

Is there a reason you need to take it apart?

I have 3 N's and have never had a reason to to try to remove the plate and don't think I even would want to unless it was jammed.
I don't trust that old metal especially when it's pinned like that. I've broken too many things trying to get those pins out.
I just broke a clutch gear on a motorized tuner trying to push a taper pin out.

If it's working leave it alone.

Chuck

[JerryVan]

Is there a reason you need to take it apart?

I have 3 N's and have never had a reason to to try to remove the plate and don't think I even would want to unless it was jammed.
I don't trust that old metal especially when it's pinned like that. I've broken too many things trying to get those pins out.
I just broke a clutch gear on a motorized tuner trying to push a taper pin out.

If it's working leave it alone.

Chuck

There's no reason to remove the pins. The cover should closely slip over them. Still, a delicate removal. If the cover does not come straight off and gets "cocked" during removal, it could break out the casting near the pin/s. It's most likely stuck to the housing with dried oil.

[Morell1]

Thank you!

Unfortunately, it's not quite working. The mandrel encounters more resistance than I believe it should. The motor, which runs well on its own, comes to a complete stop when I attach the new belt.

I've taken the motor apart and am preparing to clean and lubricate it to reduce drag. I'm stopping short at disassembling the spring barrel because it seems to give good power and doesn't appear to be terribly gummed up. (It doesn't shudder.) If I need to, I'll disassemble and address that as well.

In the meantime, I'll try to clean and lubricate what I can on the topworks, using cue tips and the like. Here's hoping that it all makes a difference. I won't risk damaging any of that beautiful casting!

[FellowCollector]

I have 3 nice original Columbia N's in the collection here. It's a favorite model of mine and I have successfully removed the end plate on one of mine to replace a mandrel that had (sadly) received a small dent during shipping due to exceedingly poor packaging. Luckily for me, I found a 4th Columbia N about 6 months later that someone was selling on eBay for parts. I immediately bought it. That one had a nice original mandrel (and some other useful parts) and I replaced my mandrel with that one. I had no problem at all with carefully removing and replacing the Columbia N plate on the parts machine nor any problem with carefully removing and replacing the plate on mine. Yours sounds like it may be stuck with lots of ancient lubricant and possibly other sediment. But the plate can be removed. It was installed at the factory and it can be removed. I wish that I could help you with yours. Good luck.

Doug

[Shawn]

Morell1

Just as a suggestion, if the mandrel faces resistance when the end-gate is in place, perhaps the issue is on the other end from the plate you are trying to remove. On the end gate is a bearing that the pointed shaft on the end of the mandrel fits into. This bearing may be moved in or out to adjust the tension on the mandrel by a screw - Red Arrow in the picture. Loosening the screw pulls the bearing away from the pointed mandrel shaft, providing more room (less tension), tightening the screw moves the bearing closer to the pointed mandrel shaft, providing less room (more tension).

I cannot remember if there is an additional set screw on the back side of the end gate that secures the mandrel bearing screw. My N is still packed, and inaccessible at the moment. I just grabbed a picture from the internet.

As well, the holes on top of the bump outs in the end plate you are looking to remove are channels for oil ('ve added red arrows to your picture and attached it here). It may serve you well to put in a light machine oil (many conversations on the forum about what kind) to ensure the gears are well lubricated. Just make sure the holes aren't plugged with gunk.

Hope that helps.

Shawn

Columbi N.jpg (55.28 KiB) Viewed 2578 times

[Morell1]

I had no problem at all with carefully removing and replacing the Columbia N plate on the parts machine nor any problem with carefully removing and replacing the plate on mine. Yours sounds like it may be stuck with lots of ancient lubricant and possibly other sediment. But the plate can be removed. It was installed at the factory and it can be removed. I wish that I could help you with yours. Good luck.

Doug

Thank you. Doug. You have an enviable collection! I'm sure that ancient lubricant is gluing the pieces together on my machine.

My question to you is about the pins circled in my photograph. The pins appear to go straight through the casting because they're visible on the other side as well. Do you recall how those pins function? Are they thin and fragile? Are they embedded in some thick aluminum casting and therefore less vulnerable? I'm worried about breaking them or struggling to align them again if I remove the plate.

Thanks again.

[Morell1]

Hope that helps.

Shawn

Columbi N.jpg
PXL_20250324_230637709~2.jpg

Thank you , Shawn! I had already adjusted and lightly lubricated the bearing on the end gate to minimize resistance, and I've also lubricated the channels you point to with sewing machine oil. That did improve matters, but the mandrel still encounters more resistance than I'd expect.

There are also two channels for lubricating the feed screw. I'm planning to clean the feed screw as well as possible while it's in place and then relubricating that as well.

Thanks again!

[JerryVan]

I had no problem at all with carefully removing and replacing the Columbia N plate on the parts machine nor any problem with carefully removing and replacing the plate on mine. Yours sounds like it may be stuck with lots of ancient lubricant and possibly other sediment. But the plate can be removed. It was installed at the factory and it can be removed. I wish that I could help you with yours. Good luck.

Doug

Thank you. Doug. You have an enviable collection! I'm sure that ancient lubricant is gluing the pieces together on my machine.

My question to you is about the pins circled in my photograph. The pins appear to go straight through the casting because they're visible on the other side as well. Do you recall how those pins function? Are they thin and fragile? Are they embedded in some thick aluminum casting and therefore less vulnerable? I'm worried about breaking them or struggling to align them again if I remove the plate.

Thanks again.

Those pins are meant to locate the cover accurately*. They will be pressed into the main housing tightly but will be only a close "slip fit" with the cover. Do not think about removing them. You will not break those pins. They are not delicate. Removing them is totally unnecessary and will put the surrounding aluminum casting under high risk of damage.

*They are alignment pins. Since the position of the end cover is critical to the alignment of the two shafts that you see protruding, it was necessary that alignment pins be used so that the cover would go on exactly the same way every time.

[Morell1]

I had no problem at all with carefully removing and replacing the Columbia N plate on the parts machine nor any problem with carefully removing and replacing the plate on mine. Yours sounds like it may be stuck with lots of ancient lubricant and possibly other sediment. But the plate can be removed. It was installed at the factory and it can be removed. I wish that I could help you with yours. Good luck.

Doug

Thank you. Doug. You have an enviable collection! I'm sure that ancient lubricant is gluing the pieces together on my machine.

My question to you is about the pins circled in my photograph. The pins appear to go straight through the casting because they're visible on the other side as well. Do you recall how those pins function? Are they thin and fragile? Are they embedded in some thick aluminum casting and therefore less vulnerable? I'm worried about breaking them or struggling to align them again if I remove the plate.

Thanks again.

Those pins are meant to locate the cover accurately*. They will be pressed into the main housing tightly but will be only a close "slip fit" with the cover. Do not think about removing them. You will not break those pins. They are not delicate. Removing them is totally unnecessary and will put the surrounding aluminum casting under high risk of damage.

*They are alignment pins. Since the position of the end cover is critical to the alignment of the two shafts that you see protruding, it was necessary that alignment pins be used so that the cover would go on exactly the same way every time.

Thank you, Jerry! That's helpful to know. I had assumed that the pins were embedded in the interior casting and protruding only far enough to help with plate alignment. I have no intention of removing them, but I wanted to make sure that I had the right conception of their fiction before proceeding. Your description is very helpful!