Member postings for john barnes 4

Hi Andy, you definitely made the right choice. I am a long time Boxford owner and would highly recommend the model A. I would expect to find a decent one privately for the price you quoted. Good luck with the search.

John

I had the same issue with a cheap caliper. It was a pain to clean so I decided to de-magnetise it. I thought if it works great, if not then I will get a new one. That was two years ago and it is still working fine.

John.

No need to apologise Brian I welcome your input.

John

Hi Brian, I am not absolutely sure but I think one pair of gears is keyed and the other pair not. I tend to avoid using the bad gear unless I need it for screwcutting.

John

I have been searching for gears using Boxford as a keyword but I am going to omit Boxford from my searches from now on just in case there is another maker such as Raglan or Drummond using 16dp gears. The gear I want to replace is a 16 tooth / 32 tooth combination. I also have a couple of 32 tooth gears showing signs of wear which I will change if I can find them cheap enough or can find the cutters I need to make them. The gearbox was dismantled and all gears cleaned and deburred where necessary, oiled and replaced. It is working better than it was but when the 16 / 32 combination is selected it sounds noisy and feels rough. I wish I had taken pictures of the strip down so you could see the damage but it did not occur to me.

Thanks for that info Brian. I have had a quick look for the gears that I think I need. One in particular seems very uncommon. It may be cheaper and quicker to make my own.

Thanks for all the replies guys. I know the gearbox gears are definitely not 18dp because they would not mesh with my change gears when I stripped the gearbox last weekend. Unfortunately I can not try them with my back gears as Bazyle suggested because the gearbox is now reassembled and re fitted. I assumed the back gears were the same as the change gears. I am leaning towards 16dp and 14.5 degree pressure angle. I am going to try Williams link to confirm pressure angle. If I am correct does that mean I can use Myford gears. I know they will need to be adapted but they seem more readily available and much cheaper.

Hi all, I need a couple of gears for my Boxford model A gearbox. I have identified them as 16dp using the formula - number of teeth plus 2 divided by diameter. Can anyone confirm that is correct. Also does anyone know the pressure angle.

Good find Emgee. I wish mine had been as easy as that to set up. John.

That sounds like good advice Martin. I did not think to check the VFD. I am sure I have seen a thermal overload setting of 80 degrees in the parameters. I will check it out tomorrow. John.

For those of you who are interested the link provided by mgnbuk is for a 1.5kw VFD mine is a .75kw. Mine does not have the cooling fans but other than that appears almost identical. Martin and Dave both expressed concern about the motor getting too hot. I ran the motor today at 50hz for 20 mins. and it remained completely cool. Just to test it for tripping I increased it to 85hz and it was ok. John.

Could the pulley be slipping on the shaft and causing friction. Check you have a woodruff key in.

Dave / Emgee not let the motor run for very long so far so not sure if there is an overheating problem. Unfortunately I have no wattmeter or any other test equipment. I got my readings from the VFD display panel.

Martin, turning the potentiometer quickly did cause a trip before I slowed the ramp up speed but it seems ok now. I have tested it from the VFD and also from the remote Potentiometer. Could the display inaccuracy you mention be caused by the unit not being shielded?

John

Martin, the motor is .75kw not 1kw and is rated at 3.2 amps. when the motor is running at 50hz without load it now draws about 3.8 amps. This increases when under load to about 5amps. The main current overload P78 is set at 6000mA which was the default setting with this VFD not 3000mA as shown on the parameter settings. It was your earlier post that pointed me to the P34 setting which hopefully has cured the tripping. I dont know what you mean by VR but if you mean P42 (ramp down) then it is set to the default of 25 and seems ok.

I think I have sorted the VFD. I set the display to amps and observed what happened when the motor accelerated. The current became too high and the VFD tripped showing error 6 (over current protection). I set P34 (main rising current) to 10 instead of the default of 25. Now the VFD accelerates more slowly, the amps do not rise as high and it does not trip. Thanks to all for the support.

I tried the VFD again and it tripped at 60hz. I ran it with the gear train disengaged and no load applied. It works at 50hz but any higher and it trips. I now think it may be the motor drawing too much current.

I have just had another go with the VFD. with some success. I increased the main current overload P78 to 7000 and it ran up to 75hz before it tripped. I have set the minimum working frequency to 15hz and the maximum to 65hz. Still not perfect I know but I think it will do for me. I always intended to keep using the pulleys anyway to keep the motor running near the 50hz mark. I have not tried it under load yet I just hope it doesn't trip. A big thank you to the forum members for their assistance I hope I can do the same for someone else one day.

Hi Clive, the motor and the VFD are both new.

Hello Martin of Wick, thank you for your help. P78 is set at 6000. The motor is drawing approx. 5 amps at 50hz. I assumed this would be ok. P0 to P10 all set correctly. I have P12 set for deceleration stop. I will be trying again later today

joseph noci 1, my instructions do not have a setting for P25 which according to the set up you posted is for number of poles. The VFD does have P25 so I will try that. I have P21 set to 1420 which I thought was for the rated speed of the motor. The VFD trips out at 1420 so I will increase that and see what happens. Thanks for your help.