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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 105 106 107 108 109 110 111 112 113 114 115 Next > Last >>
Thread: Log in time
16/03/2010 21:36:05
Hi,
     I am just passing the tip on. Someone else told me about it. I originally thought ticking the box automatically logged you on on subsequent visits as it does on some other sites.
Les.
16/03/2010 18:57:40
Hi,
      When you are logging in tick the "Remember me" box. That seems to disable the time out.
Les.
 
Thread: X3 mill help
11/03/2010 23:12:44
Hi MarcuSweden,
                                 I do not know anything about the XJ12-300 mill. I traced the circuit of the controller in my X3 mill when the motor failed blowing the mains fuse. I expected that the controller board would have been damage. (It had survived without damage.) I seem to remember discussion about people fitting  kbelectronics controllers to replace failed Chinese controllers. this was probably on the" X_Series_Mills" or the  "GrizHFMinimill" forum. There is a site that has pictures of  some of the speed controllers fitted to Chinese mills and lathes. This is their URL HERE  I also found a very poor quality copy of the manual for one of kbelectronics controllers  HERE
Les.
09/03/2010 21:04:54
Hi Ben,
               I think the most likely cause of the fault is one or both of the SCR's (Thyristors) on the controller board. Having said that you need to verify that this is the case before replacing them and also that no other components have failed. I have put the schematic of the controller board in the file section the  X_series_ mills  forum.
Unless you are familiar  with working on this sort of equipment where there is no point which can be considered as ground do not try to sort it out yourself.
Les.
Thread: Latest postings
08/03/2010 20:50:39
Hi Jason B,
                       I'm sorry I have just more or less repeated what you said earlier. I missed it due to to the loss of the full list. In fact I have missed many replies.
Les.
08/03/2010 20:44:14
Hi All,
             I think it is broke now !
If  they do not want it on the main page then why not link to the longer list with with something like "Full list" placed after "More topics"
Les.
Thread: Bandsaw speed control
07/03/2010 20:17:48
Hi Robert,
                    I agree with Jeff's comments. The motor will be an induction motor so you can not use a simple phase control speed controller like you would use on an electric drill. The only way to vary the speed would be to use a variable frequency supply. The motor would probably not even start with the supply frequency reduced to about 5 HZ. The supply voltage would also have to be reduced so I do not think you will be able to find any speed controller that will meet your requirements. (At any price.)
Les.
Thread: Tachometer design
03/03/2010 16:17:38
Hi David,  (David Clark)
                                          My last post was a reply to Dave Tointon's post. ( I made an error writing David instead of Dave.) Sorry if it caused any confusion.
Les.
03/03/2010 15:54:21
Hi David,
                  The article (If accepted.) is only intended to give enough information to enable someone with little or no electronics knowledge to build and install the tachometer on a lathe or mill. MEW would not be the place to teach basic electronics and PIC programming. The source code will also be available on a website for those that are interested in understanding how it works. (Or for people to modify to suit their own special requirements.)  One of the electronics magazines would be the best place to start to learn electronics.
Les.
Thread: Convert cheap digital calliper to height gauge?
01/03/2010 20:00:20
Hi Marcus,
                     There was a recent discussion on the "Yahoo GriZHFminimill " forum dealing with this subject. This is one design mentioned there.
Hope this helps.
Les
Thread: Hand scraping
24/02/2010 22:19:44
Hi Tony and Ramon,
                                        I think your last posts combined would make a good article in ME or MEW. I have made a point of copying them into a word document for future reference.
Thanks for the very well presented information. Also thanks to Gordon for asking the question in the first place. It made me remember my father re doing the big end bearings of his Morris 8 when I was about 10 years old. (about 56 years ago.)
Les.

Thread: Tachometer design
23/02/2010 18:16:06
Hi Harold,
                   Most of the changes on the website are as a result of things I find that need to be done before the information is in a form that can be submitted for publication. It is also a result of me trying to fully understand how to manipulate files on the website. At first I just used Microsoft Frontpage Publish function to create the website without really understanding what it was doing. The 3a version  software is a result of me noticing I had not put leading zero blanking on it. This has now been added. Also in the parts list the Kingbright display has been removed as the pin layout is slightly different to the Avego display I had used originally.
Les.
Thread: Lower Price Optical Rev Counter Accuracy
23/02/2010 14:34:44
Hi all,
           For Windy (And others that may be interested.) here is a way to see the current mains frequency on the UK grid.
The odd thing is the analogue display always seems to show less than 50 HZ while the digital value varies slightly above and below. My cheap optical tachometer seems to agree pretty well with this display.
Les.
Thread: To Web Master
23/02/2010 11:36:29
Hi,
      Many thanks for removing whatever was causing the problem on that post. I think I know what caused it I used "Word" to check the spelling of "fluorescent" and then pasted it into my post. I think some formatting characters characters must have been pasted in as well.
Les.
 
23/02/2010 09:52:57
Hi,
      After adding a post (About 09:40 23/02/10) to the thread "Low Price Optical rev counter accuracy" the view of the page was totally confused. I think there must be some hidden characters confusing the browser. Could you try deleting this post to see if it clears the problem.
Les.
Thread: Lower Price Optical Rev Counter Accuracy
23/02/2010 09:35:45

I agree with Frank. Although the mains frequency is 50 HZ a normal fluorescent lamp (NOT A LOW ENERGY ONE) flickers at 100 HZ. A three jaw chuck rotating at 1000 RPM would appear to have six jaws. Overnight I had the idea of trying to blank off the illuminating beam from my optical tachometer so that pointing it at a fluorescent lamp would enable it to see the 100 HZ pulses of light. On looking at the tachometer I found that both the source and detector were behind a lens so there was no way to block the light. I thought I would try it anyway. It worked reasonably well at about two feet away from an 11 watt desk lamp or about three feet from an 8 foot tube.The reading should be 6000 RPM for exactly 50 HZ mains. At different times I had reading between 5992 and 6013 RPM (6013 reading would indicate a mains frequency of 50.11HZ)
On the subject of the ignition strobe it will not flash at 50 HZ unless it is being triggered from an engine running at 1500 RPM (Assuming a 4 cylinder 4 stroke.) To use it without being triggered by an engine some way would have to be found to generate a trigger signal. This could be as simple as a squaring circuit fed from a low voltage transformer or as complex as a precision signal generator. I do not think it worth the effort when a fluorescent light works well enough.
Les.

Edited By David Clark 1 on 23/02/2010 10:51:43

22/02/2010 19:57:12
Hi Roy,
              The width of the tape does not matter so long as it is not so narrow that at very high speeds the width of the pulse produced is too short to be seen. (Or it covers such a small percentage of the area seen by the detector that it does not reflect much of the light back)
The same reasoning would apply if the marker covered almost all of the cercumference leaving a very small area unobscured. I find that the type of tape used is not critical. If the object is shiny I would use black insulating tape. If the object was dark I would use a light coloured tape.
Les.
 
 
22/02/2010 19:17:05
Apologies for the multiple posts. My broadband connection dropped out (Which it does quite often at busy times.) and I thought the post was not sent.
Les.
22/02/2010 18:20:36
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.
22/02/2010 18:17:08
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.
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