Hello fellow enthusiasts I have a brand new KT-VS1, just purchased. I’ve changed the belt and all was fine until I pressed rewind, which was noisy and I have now discovered the reason: the tiny plastic gear connected to and situated under the spindle has a split in it, so it is fractionally oversize now, hence the noise. It’s the gear that engages with the main drive when the rewind panel is pressed (which presses down the sprung rewind spindle and thereby enables the gears to engage), so I’m looking for a replacement or tips about how to undertake a repair of the existing gear. I guess realistically my only option is to buy another unit, but in ‘spares or repair’ condition and hope the relevant gear is ok within it (but maybe if this is a common issue with these units, I might just end up with another cracked gear). Equally if you have an alternative suggestion on how to get a new gear, or whether the one I have could be repaired, happy to hear about that. If anyone can offer any help, I’d be very grateful. David
Hello and welcome to Stereo2Go. Is the crack in the gear a radial crack (from the centre outwards)? It may be possible to repair it using polyester resin and carbon fibre. I repaired a cracked nylon gear on a WM-22 a while ago. Over time the nylon had shrunk and the steel spindle hadn't, so the gear eventually cracked. If a similar thing has happened on the KT-VS1, then if you buy a spare unit, it may well have the same problem. Somebody had previously tried to repair the WM-22 gear using a lump of glue. I cleaned off the old glue and scored a groove across the crack and filled it with carbon fibres and resin. Carbon fibres are very strong under tension. Once it had set I reamed out the centre hole so that it would fit snugly onto the spindle. Before repair. After repair.
This is really useful and is what I am coming to understand about these units and how to repair them. Yes, the crack is radial (a clean vertical crack), and I’d heard about the likelihood of the plastic gear shrinkage over time causing the split given that the steel spindle retains its original size. My repair approach will I think have to be different though as it is a very small gear (let’s say around 3-4mm diameter, a bit like the pinion you’d see on an old scaleextric car motor), and so no space to do the type of repair you did. I’m wondering if my best bet is to -remove the gear from the spindle, -get some glue into the crack (superglue perhaps?) -gently clamp it to close the crack up, - once dry, ream out the centre hole so it fits the spindle properly, -refit, possibly gluing it to the spindle. Is that going to be the best option do you suspect?
That sounds as if it could work. I would use a slow curing epoxy or polyester resin rather than superglue as it will be a lot stronger. Superglue is OK to use on non load or stress bearing joints, or to hold parts in place temporarily while applying resin, but it is not a very strong adhesive. If possible, I would try and rough up the inner faces of the crack using a fine wet and dry paper, to key the surfaces. Make sure the surfaces are clean and free of grease when you apply the glue. Before gluing the gear to the spindle, check that you won't need to remove it in the future if you need to dismantle the machine or access parts underneath it.
Good advice - thank you. I’ve heard that slow curing epoxy enables the epoxy to ‘soak’ better into (in this case) the nylon gear, so making the bond stronger, and that it often cures slightly ‘rubbery’ rather than hard, I wondered if this latter point might lead to a slightly more flexible (rather than hard/brittle) bond, which might make for a more elastic and hence secure fit to the spindle, so I would not need to glue the gear to the spindle. Does that sound about right? If you have any specific glue recommendations (make/name) for a uk buyer, let me know.
So here now is a picture of the gear. It's tiny - approx 5mm diameter, and you can see the crack very clearly. I've now removed it from the spindle to repair it. I'm wondering how I'm going to get a 'thick' epoxy glue into the gap, and how best to clamp it to close the gap. Any advice anyone?
I think I would repair the gear in two stages. I would use polyester resin, which is a bit runnier than epoxy adhesives sold for domestic use, such as Araldite. I use the polyester resin which is included in the "Big Boy Fibre Glass Repair Kit" which is available on Ebay. You will also need some miniature digital scales to measure out the resin and hardener and a suitable disposable container to mix the resin in. For the first stage, I would bond the crack closed. For the second stage I would wrap some fibreglass strands or carbon fibres around the top plain part of the component, above the geared part (assuming that doing so will not interfere with the operation of the gear or the mechanism). The fibres are strong in tension and will help keep it closed. Having done that, you will need to ream out the centre hole so that it will fit on to the steel shaft without putting undue stress on it. Prior to bonding, use some wet and dry paper to rough up or key the surface you want to bond, including the inside surfaces of the crack. Use the resin sparingly and carefully. If you use too much it will get into places where you don't want it to and harden. Then you will have a nightmare job removing it. After applying the resin inside the crack for the first stage, clean off any excess resin and use a clothes peg to hold the crack closed. Resin doesn't stick to cling film so place a cling film barrier between the gear and the clothes peg. The resin should go fully hard after a couple of days but will go through a rubbery phase first. At each stage, once you have glued and set the peice in position, leave it for 24 hours or more to set and don't touch or move it. Don't throw away the unused resin at this stage; use it to gauge how far the resin has cured. If you prod or move your workpeice to see if the resin has set, you will weaken it.
Not knowing about polyester resin, I used metal sleeves to fix cracked gears on Sencor S-4800. Discards of brass tubing available off eBay for next to nothing, old telescoping antennas supplement the set
Different epoxys seem to have wildly different drying times. Last weekend I bought and used some for gluing a turntable base. The choice in B&Q seemed to be between various "5 minute" epoxys. and some cheap own brand stuff that didn't specify a setting time. Five minutes sounded too fast so I bought the cheap stuff. 24 hours after mixing it it was still quite rubbery. Hopefully the old theory that the slowest setting epoxys end up as the strongest will be true, although my repairs were only for cosmetic reasons.
I like this option, but I have very little space to play with (see pic) and it would need a very thin-walled piece of tubing. I guess that if I could find a slightly undersized piece of tubing, I could gently remove some of the body of the plain part of the gear to get it to fit and not rub on the bigger gear. How best to cut the pipe when they are so small?
I used diamond Dremel cutting wheels and also X-ACTO Blades. X-Acto sold for wood but they cut brass/chromed brass/aluminum tubing like butter From my last photo you can see that I had this same problem. I set brass tubing (over a drill-bit) into a drill, then at low speed shaved off extra thickness with diamond file.
Five-seven years ago I bought Brampton epoxies: 5-min and ExtraStrong sets. Figured that if it is strong enough for golf clubs, it should be good enough for me. Never had to buy epoxy syringes since, the only trick is to warm the bottles to 30+ degrees C before mixing. Repeat warm-up of the whole bottles did not seem to affect anything. Now I will definitely hunt down Polyester resin, as @Deb64 suggested
OK, so here's an update, and I have to say I have a very pleasing outcome, pics attached. Once I'd seen the idea from Jorge about creating a metal sleeve, it immediately struck me as the best solution as it represented a very similar approach to how servos are strengthened in radio control stuff, which i used to be into. So I did the following: 1) carefully measured the blank end of the gear piece and estimated what size it would be closed (bang on 3mm I thought). 2) Purchased a 3.5mm outer diameter K&S brass tube, thin walled (0.225mm, as a needed to make sure this gear didn't snag the larger one, not much room to play with) off eBay for about £3.40 posted, which arrived today. 3) The tube came in a 30cm length, which was great so I could hold it properly whilst squeezing the gear gently to close the crack and see if it fitted. It did, pretty much perfectly, though I tried both ends of the full length tube, and one end felt like a tighter fit. 4) marked out the length of tube needed, using some masking tape wrapped around the tube to make it clear, and then cut it using a Dremel and appropriate circular blade 5) applied a tiny amount of superglue via the tip of a pin into the crack, and fitted the tiny brass sleeve. Very fiddly but I got it on eventually. 6) I then tried it on the spindle, and it was too tight, leading to the crack opening up on the gear-end of the gear, so the teeth were no longer uniformly positioned and so the winding action was noisy and clunky. 7) I then used a 1.6mm drill bit on a slow setting on my Dremel, holding the gear on the bit, and gently increasing the size of the mounting hole. I did this 3 times, going back and forth with re-fitting the gear to the spindle, and eventually had a very nice snug fit but with no fractional opening up of the crack. Having tested the winding on this spindle, it is now smooth and quiet - perfect result. Job done, and thanks everyone for the advice! The player now functions perfectly, and sounds great too!
