By continuing to use this site, you agree to our use of cookies. Find out more

Member postings for Les Jones 1

Here is a list of all the postings Les Jones 1 has made in our forums. Click on a thread name to jump to the thread.

<< First < Prev 106 107 108 109 110 111 112 113 114 115 Next > Last >>
Thread: Lower Price Optical Rev Counter Accuracy
22/02/2010 18:16:46
Hi Windy,
                   I think your optical tachometer is more likely to be correct than the speed marked on a motor or a mechanical tachometer. With no load on an induction motor that is marked 2800  RPM its speed will be close to synchronous speed which is 3000 RPM. A motor rated at 25000 RPM will be a series motor. The speed of these varies greatly with load. I have combined optical and direct drive tachometer which is probable similar to yours. The readings from this agree with a home made tachometer that was originally tested using an audio signal generator and frequency counter. The optical tachometer will almost certainly use a crystal as a time reference. Even the cheapest crystal will have an accuracy measured in tens of parts per million. (Even 1000 parts per million is 0.1% accuracy)
Les.
Thread: Diamond tool holder.
21/02/2010 12:06:06
Hi Chris,
                  This is a reply to your post at 18:43 yesterday. I went down to my workshop this morning to have another look at the tool holder. I milled the top of the clamp screw flush with the side face of the holder. (Rather than facing it in the lathe.) This gave me the required clearance and left enough metal left on the screw head. I have put a few pictures of it on an experimental web site I am building.
 I did try ticking the remember me button a few days ago and it seemed to solve the logging out problem but I forgot to do so yesterday.
Les.
20/02/2010 18:06:36
Hi Chris,
                 When I thought about Meyrick's comments about the geometry of the diamond tool and the tangential tool I realised he was right. Whichever way the tool bit is griped it is still presented to the work piece  in the same way. Looking at the picture on page 14 of issue156 (The bottom of last page of the article on the tangential tool.) the picture of the diamond tool looks like the bit is held in a V grove and clamped on the opposite corner. I originally thought that the shank was straight but on closer inspection I think front has a bend in it. I have looked at the diamond tool website but I am still not sure exactly how it is made. I will make a point to see if anyone is selling them at the Harrogate exhibition in May. If so I will have a closer look.
I made a scaled up version (To take 0.25" bits.) of the design in issue 156 today and it seems to work well. The only problem I can see is that facing the end of a large bar I think the tool clamp screw may hit the work piece. I only tried it on small diameter bar.
 
I just found I had been logged out when clicking the post button but using the back arrow on the browser displayed the page I had just typed which enabled me to copy it before logging back in.
Les.
Thread: Hot air and stirling engines
18/02/2010 18:17:11
Hi,
         I am having the same problem with the adverts. I have tried Firefox 3.6, IE8
and Google chrome 4.0.249.89 (Latest version I think) 
A temporary way round it is to copy and past the text to notepad etc. To copy put the cursor on the first character. Hold the left mouse button down then drag the cursor  to the end of the text. The text will now be highlighted. Now press the control key and the C key together. This copies the text to the clipboard. now got to notepad and press control and V together. The text will appear in notepad.
Les.
Thread: Diamond tool holder.
18/02/2010 14:55:29
Hi Circlip,
                The diamond tool holder is slightly different to the tangential one. Instead of the tool bit fitting into a slot it fits into a V grove.This means the  corner of the bit points towards the work piece when the tool holder is perpendicular to the lathe axis. With the tangential tool one edge of the tool bit would be almost parallel with the work piece.
Les.
18/02/2010 08:53:00
Hi Chris,   (Chris S)
                             I for one would be interested in making one of these tool holders
If you can find the time to write it up. I think writing it up probably takes longer than making it. I certainly found this when I started to get my tachometer design in a form that could be published. I keep thinking of things that need adding like static precautions and explaining resistor colour codes.
Les.
Thread: Heat Treatment of I/C Cylinders
17/02/2010 11:09:44
Hi Ramon and Meyrick,
                                   If my memory is correct when I was in my teens I had an ED Hornet engine (1.5 cc I think) I swapped this for an ED Bee (1 cc) I think this had a cast iron cylinder liner. As this engine was worn my father made a new cylinder for it. This was made out of cast iron. The mention of the ED racer earlier in this topic made me remember this. There was also a mention on this forum of "Keil Kraft" model aircraft kits. I used to build these when I was in my teens. I'm glad I'm not the only one that finds that they have been logged out while typing a reply. I am convinced the time out time is shorter while typing a message than when doing nothing. I sometimes resort to copying the reply I have typed to notepad before clicking on the post button.
Les
Thread: Home Casting in Mazak
14/02/2010 10:41:30
Hi Alex,
             There is a forum on the Yahoo forums that deals with metal casting.
Using plaster for moulds has been discussed but I can not remember what the advice was from experienced members of the group.
Hope this helps.
Les.
Thread: steel price
12/02/2010 11:52:35
Thanks Trevor,
                     I phone them when the weather gets better. I need to buy a 2 M x 1M
sheet of 1.6 or 2mm steel. I will have to cut this to size outside my workshop hence the need for better weather.
Les.
12/02/2010 08:30:03
Hi Trevor,
               It looks good value to me. Would you be prepared to say which stockist you used as I need to buy some 2 mm sheet for a furnace I am building and some bar about 25mm x 10mm to make tongs to lift the crucible.
Les.   (Ormskirk - not far from Liverpool.)
Thread: Boring Question
11/02/2010 16:35:22
Hi Ramon,
                  The tangential toolholder was in the Autumn 2009 (No.156) edition.
Les.
Thread: Blown X1 Mill speed control
09/02/2010 23:29:38
Hi Steve,
               I have assumed that the X1 has a permanent magnet DC motor similar to the X3.  The speed controller on the X3 uses two SCR's and two diodes in a bridge which is phase controlled. I could not find a schematic on the web so I traced it out.
(If anyone wants a copy let me know.) The only Sieg speed controller schematic I could find was for the X2 This used two mosfets. My understanding is that Olivers controller has only one power device. I do not know how Oliver knew it was IGBT. It should be possible to test the controller when ALL the fault components have been replaced using a 100 watt light bulb as a load. (This works on the X3)
A warning to Oliver. If you think about looking at signals with a scope you will NOT be able to do so with it powered from the mains. THE CONTROL CIRCUIT "GROUND" WILL BE LIVE SO YOU CAN NOT CONNECT THE SCOPE GROUND TO IT. To test it safely you will need a floating supply.
Les
09/02/2010 08:19:59
Hi Oliver,
               Have you checked the motor resistance between all commutator segments. What I mean is connect your meter across the motor, note the reading, turn the motor a few degrees and repeat the test. Do this until you have done one revolution. the reading should be about the same in any position. If it varies much then there is a short or open circuit on the windings. Either fault could kill the controller board. When the motor failed on my X3 two windings had shorted together and one winding went open circuit. I was lucky it just blew the fuse. You could also try running the motor from a 12 or 24 volt power supply. If  you do not have a current limited power supply you could use a car battery WITH A HEADLAMP BULB IN SERIES TO LIMIT THE CURRENT in case there is a short at one position.The motor should run smoothly (But at about 5% of its top speed rating.)
Les.
Thread: Slow loading pages.
07/02/2010 16:22:46
Hi all,
           The other day  I came across  a tip on the web for way of possibly improving your broadband connection speed by up to 15% The original tip suggested fitting a product BT sell called an "I Plate" this fits to the new type BTNE5 master socket.
I did some more research to find out what it did. It is a filter on the bell wire. This led me to another tip which said to save buying one of the just disconnect the bell wire (Terminal 3 in the master socket.) If you have OLD phones you cannot do this as it will stop the bell working. If all your phones are fairly new then they only need the two wires. I was doubtful if it would work but I tried it anyway. It did improve the speed in my case.
Les.
07/02/2010 12:53:30
Hi Ramon,
                 I have just tried loading various forum posts and the seem to load at a reasonable speed. (About two seconds) I do not know about yesterday.)
Les.
Thread: Spindle Speed
04/02/2010 22:50:37
Hi all,
            I have a program that someone sent to me that is designed to produce the pattern for optical encoders. This could be used to produce strobe disks that can be printed out.
If anyone woulld like a copy send me your email address on this forums message system and I will attach it to an email.
Les.
Thread: Tachometer design
02/02/2010 09:20:43
Hi Neil,
             If you look back through this thread you will see that I suggested using hall effect gear sensor in the situation where sensing teeth on an existing gear on the machine is the simplest option. These have the magnet built in and automatic threshold adjustment so that the gear to sensor distance is not critical. There are two types of these. The two wire type requires a sense resistor in series with it (About 100 ohm is suitable.) The three wire type which would be ideal as it could be connected directly to the PIC carries a one off import charge of  £15.95 which makes them too expensive to buy in one off's.
The part number of the two wire type is ATS642LSHTN (Farnell code 1521698) I used a device similar to the one you suggest with an external small magnet on my mill and that works well. For situations were there is no existing gear to sense then a reflective optical sensor is easy to install fitting it close to a rotating part with a reflective marker stuck to it. Both the two wire gear sensor and the optical sensor require an adjustable threshold. The design is aimed at non electronics people so I wanted it to be simple to use with either sensor. (If the unit was limited to using the exact hall device I suggest then the threshold could be set to a calculated value with fixes resistors.)
Les.
 
01/02/2010 16:02:20
Hi Neil,
           There is no reason why an internal analogue comparator should not be used.
It would require a PIC with three more I/O pins as I can see no way in firmware of internally routing the output of the comparator to the CCP input so it would have to be hard wired between the comparator output and the CCP input. I do not think this would improve the performance in any way but it may save some space. Removing an 8 pin IC but requiring going from an 18 pin PIC to a 28 pin one. I am making the source code available as well as the hex code so anyone can modify it to suit their requirements. (Or decide after looking at the code they do not like the design and go to another design.)
Les.
01/02/2010 15:49:08
Hi all,
This reply is to Hugh Gilhespie's  of Jan 31st
I think your offer is very kind as it would bring down the cost.
I did a costing of parts from Farnell and Rapid. Farnell worked out to £8.23 and Rapid £5.87 including VAT This is on the assumption that resistors could be bought in units of one. Farnell minimum is 50, Rapids is 100. For someone buying the parts for one unit (From Rapid ) they would have to buy 680 resistors more than required which is
£3.40 + VAT which is  £4.00 They would then have to Pay postage which is £4.95
(On orders under £30.00) The total cost for one would come to £14.82 which would make it too expensive. This does not cover the cost of stripboard  and bits of wire or a PCB A problem you would have is having some idea of the numbers involved. If the numbers were high then a manufactured PCB would be the best solution. I have tried to do a PCB layout with "Eagle" software but I have not yet mastered it properly. I would be happy to program the PIC's If you want a copy of the costing spreadsheet send me a message on this forums messaging system with an email address so I can send you a copy. (I would not advise putting a email address in this part of the forum as it may result is you receiving spam.)
Les.
 
Thread: To Web Master
31/01/2010 09:59:02
Hi all,
          For someone to look into this problem they will need to know which browser and operating  system suffer with it.
Les.
<< First < Prev 106 107 108 109 110 111 112 113 114 115 Next > Last >>
Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Sign up to our Newsletter

Sign up to our newsletter and get a free digital issue.

You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy

Latest Forum Posts
Support Our Partners
cowells
Sarik
MERIDIENNE EXHIBITIONS LTD
Shopping Partners
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest

 

Donate

donate