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

Member postings for David Colwill

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

<< First < Prev 34 35 36 37 38 39
Thread: Boring with carbide inserts
24/12/2010 00:32:01
    I have some alpha mill cutters from cutwel which are milling cutters with tct inserts. I have never had very good results with them and the inserts would chip really easily no matter how "careful" I was.
    When confronted with a job which required quite a lot of work with a 20 mm end mill I decided to have 1 last try with them before giving up in disgust. I looked on line at the hertel site (they produce similar cutters) and found a speed and feed calculator. I entered all the details in and Bingo 1500 revs at 250mm / min. Way faster than I would have gone in both speed and feed. The result.... For the first time the cutter sounded "happy" doing what it was made for.
    So I would now tend to stick with the recommended speeds and feeds and drop down if things don't sound right.
Thread: Chuck Salvage?
20/12/2010 08:23:11
Might be worth looking at the post "restoring a steam engine" in beginners questions as several methods were covered in that.
Good luck.
Dave.
Thread: HSS v Carbide Tipped Tools
16/12/2010 12:48:44
   I started using carbide about 5 years ago when I got some DCMT toolholders with a second hand Emco CNC. These are the smaller 07 size. I too had problems adapting but decided to persevere. I do quite a bit of work in plastics and aluminium, so I started buying the correct grade of tip which makes a huge difference. This lead  me to buying other grades for cast iron and stainless which again offer improvements when used on the appropriate material and of course tip radius (finer for finishing).  I am fortunate that I get paid for 85% of my work so I can buy these tips at my customers expense hence what may appear to be a costly experiment. It is worth pointing out that companies like Cutwel will allow you to buy a box of ten tips but mix the grades (eg 4 general purpose, 4 aluminium and 2 cast iron) also if you can buy toolholders which take the same tips then this reduces the expense.
   I was originally using a Warco BH600 and could achieve good results on most materials I have now replaced this with a much heavier and more rigid machine which has improved things even further.
   The suggestion by Douglas to use an aluminium grade insert for fine finishing on steel certainly works as I have used it myself with fantastic results but be warned these tips are very delicate and will not stand much abuse.
Dave
 
Thread: My subscription is running out
15/12/2010 12:02:55
Americans having to pay more than the Brits an outrage! This would never happen the other way round, would it? Sorry lads welcome to my life!
Thread: End mills in a drill chuck
07/12/2010 19:13:07
    I am currently running a job on my Triac CNC  and am having to use a 3mm ball nose slot drill to mill a slot 12mm long by 1.5mm deep in perspex. Due to a lack of bt35 tool holders I am holding it in a drill chuck. I would rather not be doing this but needs must, I did however (being a bit chicken) program it to be done in two passes. So far it has done about 500 or so and nothing has moved. I should point out that I considered the possibilities of chucks coming off tapers and cutters walking out but as this is an automated machine there is little or no chance of this causing injury as it is largely unattended. 
 
    So I feel confident now in saying yes there is a time and place!
  
 
Thread: Bridgeport clone quill / knee conversion
05/12/2010 22:45:06
Hi Steve,
I have been looking around and I agree most commercial systems use the front of the quill. I am starting to head towards the option of motorising the knee, partly because of rigidity and partly because I like the idea of having a high speed head on the other end of the ram for occasional routing jobs. I have used steppers which seem Ok for my purposes although I will have to use gas rams to lighten the knee if I go down that route.  Let me know how you are getting along and good luck!
Dave
Thread: Astrolabes and Other ancient Instruments
28/11/2010 08:57:04
Looks very interesting.
Thanks.
Dave 
Thread: Bridgeport clone quill / knee conversion
20/11/2010 13:03:02
Hi
I have started CNCing my King Rich bridgeport. X and Y are fine but I am hovering between the quill versus knee issue. I had originally planned to do the knee by fitting a ballscrew and nut with a timing pulley mounted directly on the ballscrew and having the stepper motor underneath the table, the whole lot to be counterweighted by two gas rams. I was told that this arrangement had problems due to inertia  and that working with small drills and cutters was a problem. I then started to think about doing the quill but the issue there seems to be that you can't get the drive close enough and mounting motors etc seems problematical. Has anyone done any of this? Any thoughts?
Dave
Thread: Which New Lathe; choices, choices...
12/11/2010 10:09:19
I have had a Warco BH600 for about 5 years. I had it from new and apart from a few niggles which I sorted out as I went along I have had no trouble with it. Recently I have had more turning work and have now replaced it with 2 lathes, a Smart and Brown 1024 and a Dean Smith and Grace 13x30. I can now see both sides of the British v Chinese argument. The two British machines are in a totally different class altogether but they are considerably heavier and 4 people will NOT lift either of them. I have seen beautiful work carried out on the roughest looking machines by people who have almost limitless care and patience but this approach means that things take much longer and require more planning etc. As a beginner I would try out as many machines as possible before opting for any one in particular and I wouldn't buy one until you have had a go on it. Also remember that a shiny new lathe on its own is pretty useless, most people have the same value as their lathe in accessories and tooling (not necessarily acquired all at once) so don't forget to allow budget for tooling and other bits that you will need. 
Good luck.
Dave.
Thread: Collet Chuck
22/10/2010 11:52:27
The Warco 220 lathes were and in fact still are made by Mashtroy http://www.mashstroy.bg/c_210_t.html   I seem to remember a collet chuck being available although I can't see one listed on their website now. They maybe worth a quick e-mail though.
Thread: Eagle Surface Grinder
08/10/2010 09:39:16
I made a spraymist for my triac CNC mill and had to stop using it because I hadn't set up proper extraction for the resultant vapour. I ended up with a workshop full of choking 'fumes' which were painful to breathe and made me feel quite ill. The actual unit though was very effective. I would advise that anyone planning on using this system checks out the relevant health and safety issues for these things. Used correctly I'm sure they are fantastic And I do hope to resurrect mine when I can put a suitable enclosure around the machine.
Dave.
Thread: Coventry Easychange Tool Holders
21/09/2010 18:18:04
I use this system on my manual Bridgeport clone (2hp I think) and have had no problems so far, that said I only use up to 20mm endmills and don't  take very heavy cuts. There is a locking screw fitted which the instructions say should be tightened when you are working at the upper limits. Also I think that Denford Easimills were 1.5 hp and they used them. They certainly speed up tool changes for the sort of things I do and have the advantage of not requiring excessive z  clearance to remove them.                            
Thread: Safety
24/11/2009 20:42:32
Thought I had better check my facts on this. It turns out it was a bloke and he won $1.7 million. Ahhh no wonder they call it the land of opportunities.
24/11/2009 20:35:10
Yes well I heard that an American woman tried to sue Winnebago after a serious accident. She engaged the cruise control and nipped in the back to brew up no less! How can you protect people like that?
22/11/2009 17:50:59
I feel that I should point out the very real danger posed by the use of titanium when used as inserts for dentistry as it specifically relates to model engineers. Extensive research has shown that when two model engineers are in talking distance of each other a great deal of hot air can be produced. This sometimes superheated gas can cause almost any material to spontaneously ignite but is especially dangerous with metals like titanium and magnesium. Further to this organic materials like the ear drum can sustain significant damage if subjected to repeated exposure symptoms include headaches, nausea and  an annoying buzzing in the ear. I have recently developed a special asbestos hat which can protect the wearer from these dangers. Please send check or postal order for £300.00 to AsbestoHat Ltd for instant protection.
12/11/2009 15:09:02
I have heard that some O rings can release hydroflouric if heated also I beleive that tufnol  can give off toxic fumes when machined. I am sure that there are many other nasty things lurking around that I am completely unaware of. While like most people I read and listen to any warnings and advice on these matters (and take them very seriously) most of my experience is gained from actually doing things which on reflection is not the best way.
It would be an excellent use for this site, if it could have some kind of data base for materials and processes that pointed out some of the pitfalls, so that those of us who lack experience in some area could "gen up" beforehand . The fact that most of the articles have already been written and published should save some time. If only one serious accident were avoided it would be worthwhile.
Thread: O-ring coming off pulley when motor power is cut
11/11/2009 18:54:03
You could try a magnetic clutch I found some in old photo copiers. Ebay may come through.
Thread: "Precision" or "does NOT do what it says on the tin"
11/11/2009 18:01:50
I think that sooner or later we all get caught out with things like this I had a similar experience with a Denford Easiturn lathe where the 3 jaw chuck would not run true. after trying various other chucks borrowed from friends it became apparent that the cam loc locating taper was oversize. This on a British machine (it had obviously gone unnoticed by the school that owned it for the first twenty years of its life). I cannot see how it is possible to escape products made in the far east and anyway I don't really want to. I have had few really bad experiences with them and can afford to write them off against money saved on the good ones  and still be well in profit. One other thing about Chiwanese products, I am sure that i heard one importer of such machines saying that Colchester CNC stuff was made in the same factory and can anyone tell me where Myford milling machines are made? The world seems to be full of people all saying that their products are fantastic etc etc ... They all lie and just because I'm paranoid it doesn't mean they aren't out to get me.
Anyway you have my sympathies  and I am sure you will get there in the end.
Thread: Compressed air on lathe
07/11/2009 08:57:04
My Triac has no facility for coolant. The base of the machine is flat so any coolant just runs onto the floor! My first thought was to implement a normal coolant system but it was too much work, also all the electronics for the CNC are in the base so coolant leaks could be disastrous. The compressor does clear chips away quite nicely and I happened to have it lying around, so it did seem to be the logical way forward all be it not ideal.
06/11/2009 23:24:59
I made a spray mist for my Denford Triac Milling machine which worked very well but very quickly filled the workshop with a choking mist. I have no doubts having breathed the stuff that it is very bad for you!!! I did find though that disconecting the coolant and just using the diaphragm compressor to blow on the cutter was suprisingly effective.
<< First < Prev 34 35 36 37 38 39
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