Periodically repeated noise in unmodulated groove, broken tip?

[lulu]

Hi,

I have built my own lathe with cutterhead design by KNOP during the lockdown. I was trying to be as precise as I could, there is a oil dashpot so that the head goes down really slowly, the whole system is controlled by arduino with MIDI support, so everything can be operated from either DAW in a computer or the other way around - the lathe controller can send MIDI commands to the DAW, there is stylus heating and a infrared heat lamp above the blank, I also wanted to use vaccum suction, the custom made glass chip jar is connected to strong vacuum cleaner, suction at the tube next to the tip is pretty srong. Everything seemed to be ready. So I did my first test cuts. I am using myShank diamond and also myshank blanks, the down weight is set to 14-15grams and I also heat the blank up to 40C, the stylus heater is set to 0.4amp, I also polish te blank with wax before cutting. I tried to cut silent grooves first, I got a weird repeating noise which is pretty loud, I cannot seem to get rid of it, I tried to incerase the stylus heat but no luck, the noise is still there. Is it possible that i have broken my diamond right from the start? I really tried to be very careful with it. No jumping or falling on the blank, never touched the tip with anythyng but Q tip. Anyone has an idea what could be causing this issue? I am attaching a sound clip.

Another issue I have is with the suction system, I tried to put talc in the tube, but after a few minutes of cutting the chip starts to build up around the back of the stylus, for first few moments it appears to work just fine, but it seems that the chip never reaches the jar and gets stuck in the pipe next to the tip.. Any ideas? Anyway, I have never let it go that far so that the stylus could jump.

Thank you for any advice.. I got a lot of inspiration from this forum an finally got enough courage to ask something too..

Lukas

[ilovedrums247]

hi Lulu, nice job with the build. From my own experience with a DIY machine, I was getting a similar noise when my stylus pressure was too heavy. The grooves under the microscope went from a clean line to thick and cloudy. Not sure about the suction issue though...good luck

[SueDenim]

You might try adjusting the cut angle too.

[nikc]

Hi Lulu
I have been heating myshank blanks to 25 degrees as I read it on here somewhere and it has been working fine. But please correct me or anyone correct me if I am wrong.
I have got about 12grams on stylus but might increase as apparently helps if the swarf is thicker is picks up by the vacuum easier.
BTW I found vacuum cleaners not good for suction and bought a pump

Best
Nik

[SueDenim]

BTW I found vacuum cleaners not good for suction and bought a pump

Agreed. What you're looking for is high flow rate rather than peak suction power.
So something like a side channel blower generally offers much more consistent swarf pickup than a domestic vacuum cleaner.

[lulu]

Thank you for the tips, today i have found that the noise disappears around the center of the blank and comes back near the end again, so it is hopefully not a broken tip, but maybe some geometry problem or warped platter.. Any other ideas?

The vacuum cleaner is getting really hot, so it is probably not the best choice, can anyone give me a tip or link for a good alternative? Pump or something? I have used a vacuum pump from silkscreen table, but it was too weak.

Thanks,

Lu.

[PMST]

Im using this for a vacuum (side channel blower), I have the bigger model for 2 lathes but one will be perfect for 1 lathe

https://www.ebay.co.uk/itm/313140844694?hash=item48e8a61896:g:TP8AAOSwjXxcm3vE