stylus heating question (plastic)

[andybee]

Hello there!
I am cutting with myshank diamond, how much heating amperage is needed?
Neumann/laquer is normally 0.4-0.6A, when I set 0.5A it seems too much....
can anybody help me out?
thank you very much!

[emidisc]

In my experience as long as you pre heat the disc you don’t need stylus heating to get good cuts with virtually no surface noise - hope this helps

[misjah]

from what i remember you want the blank to be at least 30c...stylus heat didn't change from lacquer...might get longer life with more heat though.

[EposLab]

"Sold with heating wire working at 5V/0,5A"
..from Myshank website

[andybee]

thanks! it seems, best is to heat the blanks, and not the stylus.
Myshank sayd, usually no heating needed in the beginning, then heating
by listening.... every manufacturer also uses different heating wire...

[aaron]

I feel like it depends on the blanks. Sometimes stylus heating makes more noise for me than just using a lamp. I’m sure room conditions have some effect on that.

[SONARC]

Is it the consensus that stylus heating is more for the benefit of getting less surface noise, then?
How much extra stylus wear is likely to occur if it is not heated?

[d]

Definately with new stylus, blank heating to 40C - with or without stylus heating for me is the same results. Tried couple of times with different current. When too much current it seems like some crackling noise appear.

Another question is can you overheat and what consequences will lead. Can it lead to faster diamond wear? If it grinds out fast then surface noise goes up.

[HannesFTL]

Overheating is very dangerous for your stylus, it blew one of mine out of the shank(?)

New stylus not much might be needed, maybe a bit to get rid of the static type sound
Older stylus there is a sweetspot with total silence

[Dub Studio]

The answer is it really depends, there are too many variables to establish a fixed amperage. Here is my method:

1) make sure your disc is at about 25 degrees
2) start cutting silence with no heat, listen (with headphones, turned up nice and loud) to what you are cutting
3) slowly raise the current until you hear a change in the surface noise... usually the static "crackle" that HannesFTL mentions will fade away, and be replaced by a slight "hiss"
4) raise the current a little more until you hear the hiss gettting higher in frequency (like a filter sweep or woosh) and reach the peak of this hiss
5) raise it a little more, and the hiss will subside... this is your sweet spot

(bear in mind that if the stylus is quite old, you will probably not hear this at all, it only works with a new stylus, so if you need to swap the stylus out (to cut lacquers for example) make a note and use that setting again later).

Sometimes this level of current will lead to overheating, and your stylus will get clogged with melted plastic. This is often because the heating coil is simply too close to the tip, and the chip gets caught on the coil, melts, and then starts to build up, causing a loss of suction and a catastrophic fail in the cut. The simplest way to avoid this is to back off on the current, and just accept there will be a sightly higher level of surface noise. Also, double check the temperature of the disc.

The other way which works much better IMHO is to unwind the heating coil and rewind it again*, but make sure there is a little more clearance between the last winding of the coil and the tip of the stylus. Personally, I like to see about 1mm of clearance, this is easily close enough to heat the tip, but also allows the chip to clear away (although sometimes if there is a lot of static, it will build up from time to time, so keep it clean, and try to eliminate static if that's the case).

You can sometimes re-use the exisiting heating coil (as long as it doesn't snap in the unwinding process but this depends on the adhesive holding it in place, and any burnt on chip). I prefer to use new wire, because you can get much tighter uniform coils that way. If there is space, I use about 8 x windings of nichrome wire (I forget the spec, but its about 0.1mm gauage, so you are looking at about 0.8mm of winding around the stylus).

There is a danger of the stylus coming away from the shank if you wind too much coil near the hilt, so I spread the windings neatly next to each other along the length, so only one winding actualy goes next to the hilt. In this way, the heat is spread more evenly along the stylus.

*extreme care must be taken when unwinding and winding the coil, as the tip will not like being nicked by the wire. I tie off one end of the coil and untie the end furthest away from the hilt then start slowly pulling away in the opposite direction to the winding (orbiting the stylus with the wire a little tight avoids it coming into contact with the tip and helps to overcome the "tear resistance" of the glue). Don't pull too hard or the wire will snap and it's really hard to get it going again.

One final word, in my opinion glue is not necessary. It's a pain to deal with and just prevents you from getting good even contact between the wire and the stylus. A nicely wound coil will stay in place provided its tied off, and it doesn't need to be tied off tightly either. The best analogy I can think of is mooring a boat. Tie it off so the boat can move a little, but not so loose that the ropes fall off their mooring.

Hope that helps!

[d]

Thank you Dub Studio for such in depth information. It is very interesting.
Some years ago I tried to work with blanks at 25degrees but stylus weared out very quickly. So I decided not to experiment at that temperature and to keep up to 40 degrees. Of course stylus heating current was quite low.

What is your average stylus life if it is not a secret?

[Dub Studio]

Hm, good question. I don't really know, styluses seem to vary so much (sometimes they break on the first cut, sometimes I get 200 discs from the same stylus).

As far as I am aware, the temperature of the plate + the temperature of the stylus are what contribute to the "sweet spot" I mentioned. I can't say for sure if it matters whether the heat comes from the stylus or the plate. Maybe your experience tells you otherwise?

[discosdecorte]

Definately with new stylus, blank heating to 40C - with or without stylus heating for me is the same results.

Hi! I only have transparent blanks, soooo how can I heat them up to 35 or 40 C without heating the lathe too much?

Thanks for the info, very helpful thread!

[Dub Studio]

If you have the precision plate, you can use that to absorb heat from the lamp (shine it around the edge). This then transfers to the transparent disc quite quickly and easily. in my experience, 40 degrees causes more problems than it solves. I rarely go above 30 degrees.

[d]

Dub Studio there is similar experiencies here...
Always to find sweet spot and connection in that.

But very interesting about plate temperature.
If I remember corectly 2years ago I was cutting quite a lot of blanks with one stylus. Temperature was up to 30C to blank and little stylus heating - dont remember exactly but around 100mA of current. After changing to new one I get less cuts with one stylus.
Anyway, that is very interesting. Maybe you are right that a lot depends on stylus and blanks. Also correct setup.

[Dub Studio]

I think you have to weigh up the pros and cons. Yes there is a lot variation between styluses, but that is not something you can control. It's luck a lot of the time.

The things you can control are the temperature of the disc, and the stylus. So, my argument is that its better to focus on successful cuts because a) aborted cuts get very expensive, b) the difference in stylus wear between 30 and 40 degrees is not going to be huge (neglibible compared to lots of wasted dubs) and c) its very difficult (if not impossible) to do an A/B test of various temperatures (since wear is very gradual and not all styluses are the same) so it makes sense to go with the one that works for you.

I prefer to cut on the cooler side, because I waste fewer dubs - even if my stylus might wear out quicker. I mean, resharpening is equivalent to say 10 or so dubs max? If you are trying to make a stylus last a long time, and the swarf is being a nightmare, its a false economy.

I find that if I cut hotter than 30 degrees, the swarf is a real pain. It melds to the stylus more often, and the static can get crazy. I don't want to use lots of thick lubricant because time is money and that stuff takes ages to clean. Plus in the middle of summer I don't want to be adding yet more heat to the studio.

So my advice is use minimal lube, use as much heat as your lube allows, and get your styluses resharpened regularly.

[discosdecorte]

If you have the precision plate, you can use that to absorb heat from the lamp (shine it around the edge). This then transfers to the transparent disc quite quickly and easily. in my experience, 40 degrees causes more problems than it solves. I rarely go above 30 degrees.

Thanks for the tips!

[emidisc]

And what adhesive do you guys use? I’ve tried the dentist route(no pun!) and they look at you like your MAD & doing a spot of DIY Dentistry

[Dub Studio]

And what adhesive do you guys use? I’ve tried the dentist route(no pun!) and they look at you like your MAD & doing a spot of DIY Dentistry

There is usually enough tension in the wire to hold it in place. I wind it reasonably tightly, and then tie it off, leaving a bit of slack so the head can move freely still.

[emidisc]

Thanks for your reply, when you say “tie it off” do you simply knot the 2 ends of heater wire around the sapphire/diamond ?