Member postings for Barry Smith 4

If it's of use to anyone I have edited the online copy of the Lenz LPA 1s manual to make it more readable. If I can workout how to I will post it on this site. In the mean time pm me if you would like a copy of the pdf.

Barry

Hi, I had some old anilam scales and I am pretty sure they were differential square wave. If so you can just connect one of each pair to a cheaper Chinese style dro box.

However, you can't connect single ended Chinese type scale to a dro box which has a differential input without adding electronics.

Do you know why the scale failed? Sometimes it's the blub/led in the read head which can be replaced, or the alignment of the read head which can be adjusted. To do either you really need a scope and some degree of electronics knowhow. If your really tight on budget I would be willing to have a look but you would need to get the read head and scale to me (NG4 3DB)

There are a lot of cheap scales and dros around on ebay at the moment. A guy also based in Nottingham cbr electronics sells good cheap kit and will also fit it. My only word of caution is that 5 micron scales on the cross slide might not give you the resolution you want in comparison to the Newall you have been used to. I have a Chinese 5 micron system fitted to my mill and lathe and on the mill they are fine but not 100% convinced on the lathe cross slide.

Cheers Barry

When replying I forgot to mention an incident that happened in our lab back in 1988. A cleaner who was not very with it pinched a 1l bottle of HF acid and fortunately told his flat mate that he had decanted it into small plastic tubes so that he could throw it at potential attackers on the tube/streets. Fortunately, he had his collar felt quite quickly by the bill and we got it back. Things are now much tighter although I sometimes regret this when needing to do some case hardening .

Barry

Hi, being a chemist for more than 45 years I would not let it near a child or adult outside of a workplace or laboratory where people have access to an antidote and have been trained. Those using HF to dissolve rocks used to say its better to not wear gloves as if you have a pin prick you won't know it as HF and ammonium bifluoride / ammonium fluoride does not burn the like sulphuric etc. By the time you feel the burning sensation it will be too late and you can't just wash it off. You also have inhalation hazards with these compounds which can be severe.

Using the ammonium bifluoride as a paste is marginally safer than HF as its less concentrated in terms of fluoride ion concentration. On contact with water it ionises to produce the acid F and H ions hence is acidic. As you say the F attacks the glass,

I hope this help Barry

The above said, it was being used in the USA for cleaning car wheels at car washes until 2000!

Hi, Terry not sure where you are based but I have a bijur unit that used to be fitted to a bridgeport it's missing a few parts but could be got working it's clean I am in Nottingham. An alternative may be to use a higher pressure pump rather than the centrifugal high flow low pressure pump you have. The sort of thing that most fuel injection systems use to run petrol from the tank to the injectors. Or a middle ground might to use a std electric petrol pump for a carb engine these can give a combination of flow and pressure. The flow might be a little pulsed but adding a damper vessel might help there. Alternatively there are chemical dosing pumps out there that can give much higher pressure I bought 3 cheaply to use myself but have never got round to testing them out. In all these situations getting a clean return flow into the pump is critical so that needs to be given some thought that's one are where the centrifugal pumps are advantageous and have dominated the market?

Barry

Hi, I've been a water chemist for more than 40 years. You need to store the electrode in KCl solution and if dead they can be revived with 2m HCl. Ideally don't store them in distilled water. I think it's 2m KCl but will check. You calibrate the meter using buffer solutions at pH 4 and 9 or 4 and 7. These can be purchased cheap off ebay. They are called buffer solutions because they are designed to resist pH change and hence allow an accurate calibration. Between measurements wash the bulb with distilled water and wipe with a tissue. The bulbs are made of thin glass and easy to break, then you need to replace them. Like most things the more you pay the better the electrode.

Typically only accurate between pH 3 and 10. They are a combination of a silver/silver chloride reference electrode and a glass membrane electrode.

The voltage produced between the reference electrode and the glass bulb is proportional to the log10 of the hydrogen ion concentration acording to the nernst equation. Hope this helps

Barry

Hi, I have played around with P34 (main rising velocity) the default states 10 hz/s. Mine was set at 5 so changed it to 2 Hz/s and seems to have worked. Monitoring the 240v ac in gives less of a peak and just keeps below 10amps. Running at 50H the motor is taking 8amps. Looking at the 380v line it gives around 4amps which sounds about right on one of the phases.

I am measuring amps with a clamp meter that gives 100mv per amp, so not sure if that's rms or not.

Barry

Hi, I have a XYZ AT4 vfd working on my mill at lower speeds on either winding and its fine. But on the 2 pole motor and the two highest speeds it blows the mains 240v 10amp fuse. So I guess the higher torque is causing an excess inrush current to blow the fuse. The derating on the drive is OK, but I guess the 10amp is probably marginal but not had this on other vfds I have installed in the workshop.

I need to check the current with a camp meter but thought I would try to find if I can set the right parameter to at least limit any startup current. I'm looking at p24- overload protection buffer time, p34 -main rising velocity and p66-input stabilization time. Has anyone any advice on the best parameter to change?

Thanks

Barry

Hi, I went down a similar route with both of the manual bridgeports I have owned. They both had belt drive heads which is simpler in some ways but to get to use a 220v vfd you may have to change out the motor. I always upgrade the vfd to 1 HP over the rating of the motor and have had no problems with lack of torque. The only time I had this issue was when using a diy capacitor based converter. Now VFDs are so cheap I would not even go down that route.

I tend to use filters and contractors on the mains side of the vfd but otherwise use the digital controller of the vfd to do start, stop estop, fwd/rev and the contactor for isolation. You may find that you need to change out the electronic fuse on your mains supply to avoid tripping. Never had any problems with noise on the house electrical system.

I used the transformer which came with the original electrics to power the Erskine box (until it stopped working), light and an Align power feed on the table z. I use a separate 240v suds. I did think of going over to a dc motor on the series 1 CNC I have which has the variable belt drive fitted as I have some dc control boards. DC motors can give you a lot more overload torque than ac 3 phase but this conversion seems less common, perhaps its the dc motors use in small wind generators? If your using the original BP table feed its worth your while checking and if needed replacing the wires in the control box/motor. To replace the Erskine, I used a kbb anti plugging dc drive off ebay which works fine and has the benefits of being more modern components wise and smaller.

This week I am going to try the Chinese 220V single to 440V three phase route keeping the speed preselectors on the main spindle 2 speed motors and then digital controls for for/rev, stop/start, estop and speed (it's not a bridgeport). At £80 I could not resist. I will keep you posted.

Barry