Member postings for Paul Barrett

I'm on Johns side.

Saw a sewage wagon the other day and their slogan on the back was "We are No1 in the No 2 business"

Very apt I thought.

I am also interested in these controllers as an alternative to PC's and I think they will be the future. I am especially interested in one for the CNC laser i am building. I see there are several available and most lasers machines from China seem to use them. There is only one problem for me though and that is controlling the z axis for the lifting table.

My machine is about 80% built and I am having trouble deciding how to raise the table. The table is 1200 x 600mm and is raised and lowered by screw jacks and guides at each corner. My original idea was to drive all screw jacks using one motor and a toothed belt but I have not seen one big enough in gt2, gt3, htd3 etc. It would need to be over 4 metres long. My current idea is to use 4 motors, one for each jack.

I assume I would use 4 drivers with the 4 motors. So, can I connect 4 drivers to one output from the controller? If not then I assume these stand alone controllers will not work for me. I guess I would have to use a breakout board with at least 6 axis so I can slave 4 together and use a PC with some form of software.

Anyone got any ideas please.

Attn Neil.

In issue MEW 244 you've published Alan Wains article "A drill for a budget mini drill" .

Go back 16 months to MEW issue 228 and you will find the same article.??????

Does that mean Alan gets paid twice?

Just looked at your link Neil and your page with photo's at Barrs Beacon. I am afraid your a/c recognition is a little dubious. What you think is an Ryanair A320 is actually a 737-800 and the Air France 737 is a Airbus A320.

V1 is the rejected take off max speed. It varies depending on weight, runway length and conditions etc but is a ground only speed. All other speeds are aerodynamic. Once over V1 you are committed to fly. Vr is the rotate speed and V2 is the minimum speed for climb on one engine (or 2 engines if you want to go up like a bat out of hell) (Best angle of climb) for obstacle clearance. Once reaching Aa (acceleration altitude) usually 1000 feet above aerodrome altitude you accelerate to Vfs (which on 2 engines you will probably be above) which is flap retraction speed.

Airliners are normally trimmed before take off for a V2 climb ready in case of a engine failure and re trimmed after take off when safely in the climb.

Michael.

As far as I am aware they are 15 degree which I believe is most common and supplied without question. 25 degree is only supplied on request.

I run the bearings back to back (idents facing each other) but because they are not a matched pair I use shims between the outers to obtain the correct loading. I use these on my cnc router for the ballscrews to take the thrust loads on all the axis's.

Hope that helps.

Paul.

Below is an image of a 7201-2RS bearing. You can plainly see the diiference between the thrust and non thrust faces.

Paul

Try Freecad. It was designed for Linux and is very good. Huge following and loads of tutorials available on You tube.

Michael

The Motor and gearbox came from Phidgets **LINK** and I got it via their German dealers noDNA **LINK**

Paul.

Could not include this picture with original post.

I have put a few pictures of the Quill Feed Drive I made for my Warco VMC mill using a Nema 23 Stepper with a 4.25 to 1 gearbox in my album. It is loosely based on the Peter Rawlinson unit published in MEW No76.

I recently had to bore several holes for the cnc machine I am building and I got very bored having to keep turning the feed wheel by hand so I came up with this unit which works very well. You can still use the handwheel in manual mode if required.

On disassembling the worm shaft I decided to do away with the thrust bearings and use ball races instead. The thrust is not that high so I don't think there will be a problem. This meant I had to make a new housing which was made out of steel. I incorporated a preload spacer between the bearings so I could do away with the 2 lock nuts and just use 1. I drilled and tapped the lock nut for a small grub screw with a brass cap so as not to damage the thread.

The motor plate is 10mm aluminium. The motor is a small nema 23 with a 4.25:1 gearbox with a further 2:1 reduction by toothed belt and HTD3 pulleys. I made the ends by turning a 74mm od ally ring from some cored ally bar I had and then cut it in half. The sides are made from 6mm ally plate.

The large pulley fits into a recess on the handwheel and because the keyway on the shaft is not long enough I transmit the drive via a 6mm drive pin from the handwheel to the pulley.

I have been controlling it from the main control box which controls all the feed motors on the mill ( I am using the Z axis controller) but I am now going to use an arduino to control it. A fellow forum member has kindly sent me his program for the arduino so I can control it with a separate controller.

Hope it may be of interest to someone.

Steve F.

I have sent you a pm.

Paul

When I bought my XJ9525 from Amadeal around 7 years ago I had similar noises from the motor. When I stripped it down the magnet had come unglued from the casing. Hugh replaced it F.O.C. straight away.

Edited By Paul Barrett on 14/08/2014 19:35:19

The article in MEW 219 about slowing down the 9x20 lathe with a countershaft is interesting and useful to these lathes. Having owned one for several years I have found it (after several mods) a very accurate and desirable lathe.

However, I went the 3 phase and inverter route almost imeadiately for several reasons. Whilst I appreciate the cost involved will be significantly higher than making a countershaft (apart from the time involved in making it) it far outweighs the impracality of a single phase motor and transforms the machine.

Firstly there is the initial start of a single phase which is all or nothing. If fitted with a largish chuck and a fair lump in it the machine can rock sharply when starting and with quite a bang. Not so with 3 phase/inverter and a smooth ramp up.

The chuck can also come undone if you start it in reverse again with a heavy chuck/work piece. This can be fixed by fitting a locking screw on the chuck backplate.

But the biggest problem is with the belt tensioner. It is fine when turning forwards as the tensioner is on the trailing side of the belt. But if you happen to be turning/screwcutting in reverse and with quite a heavy cut the belt will slip as the tensioner is now on the drive side and the tension is not enough to cope with the load.

By fitting a 3 phase I dispensed with the intermediate shaft and just used the v belt with the 3 speed pulleys. I fitted the motor in the original motor position and spaced it so it does not need a tensioner. I very rarely change the pulley ratio as the inverter covers all speeds and I can run it down to 5 hz (about 30 rpm) with not much loss of torque. I appreciate the initial cost is high (around £150) but I feel it far outweighs the limitation of a single phase motor.

The other essential mod to do is to fit a tumbler reverse. This is essential if you want to do lots of screwcutting cause at some stage you will need to cut a L/H thread. I used it to cut a new M12 x 1mm cross slide feed screw for the lathe as I made a new hand wheel and graduated it as direct reading and fitted thrust bearings as well.

Other mods I have done is a improved top slide mount. Again essential as the original mount does flex a bit.

If you want to stick with a single phase motor then fitting a counter shaft will be an useful mod but if you can go the 3 phase route I believe you will ask yourself why you didn't do it sooner.

I am not bothered about drilling holes or modifying a machine that maybe cannot be returned to original state. As far as I am concerned if it improves the machine it can only be better than original and after all, these machines are built to a price.

Just my opinion.

Like OMG I "bailed" but have since renewed my sub since Neil has taken over. Already the mag is so much better than before. Just need to get rid of "Teach in 2014" series and fill the pages with something more relevant to teach a beginner. You couldn't learn anything from those articles, just confusion.

Hi.

I may be able to help you. I am only 10 miles up the road from you. Send me a pm.

Paul

0.003 to 0.005 is 0.002 is it not?

Don't get me wrong i think his motors are brilliant and i may have ago at sometime. I was just thinking it must be a drawing error for a tolerance that tight which would be very difficult to machine too or am I missing something.

I think the 2 micron (0.002mm) fit limit for the crankshaft bearings is a bit ambitious. I would have a job to turn to that limit let alone measure it.