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

Member postings for Dinosaur Engineer

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

<< First < Prev 1 2 3 4 5 6 7 8 Next > Last >>
Thread: Fixing metal dowels
25/01/2011 19:12:31
Hi ! Terry,
Some toolmakers used Bees' Wax instead of grease as a hydraulic medium . Certainly smelled a lot sweeter !
Proper hardened dowels have ends that are shaped differently . One end would have a slight chamfer to guide the dowel into the hole. The other end would have a radius form so that when struck with hammer or punch, the end would not mushroom or be damaged.

Edited By Dinosaur Engineer on 25/01/2011 19:17:34

24/01/2011 22:00:01
Experienced toolmakers used to have worn reamers set aside exclusively for dowel holes . Together with proper hardened dowels,( which are slightly oversize from nominal size), these gave a nice light drive fit wthout any loctite. If parts are to be separated from time to time it's advisable to add knock out holes or use tapped dowels to facilitate easy removal. Blind dowel holes sometimes had side air holes added so that the dowels could be driven in all the way without the air pressure trying to force them back out. Or alternatively a small air relief flat could be ground on the side of the dowel. I've seen side air holes used with close fitting punches to hydraulically drive dowels out . Even seen match heads used to fill up side holes and then struck with close fiiting punch to drive dowels out.
Cheap H7 Tolerance reamers will not give the required fit for tight dowels without using loctite. Unfortunately H6 reamers are a little more expensive. Most old time toolmakers would cringe at using loctite on dowels as the main purpose of using dowels was to locate parts without any clearances in the dowel holes and parts could be separated and put back together in exactly the same position. If the dowel hole is slightly oversize it can be closed up to provide a tight hole by placing a hardened ball over the hole and given a good rap with a hammer. Don't overdo this as it can move the hole in soft metal. We never let the toolroom foreman see us doing this as it was considered bad practice ( bodge up) ! 

Edited By Dinosaur Engineer on 24/01/2011 22:07:09

Edited By Dinosaur Engineer on 24/01/2011 22:09:20

Thread: For those little fiddly bits perhaps
11/01/2011 16:06:19
This technology has been around for at least 15 years for industrial rapid protyping.
Obviously the equipment has reduced in price dramatically. It is quite facinating to see as the layers build up.I would imagine that the layer thickness resolution is now much better than it was when it was first introduced.

Edited By Dinosaur Engineer on 11/01/2011 16:09:32

Thread: Gauge Plate
08/01/2011 19:53:49
John ,
All the "quality" Gauge Plate I've ever used has been oil hardening. I wouldn't want to spend quite a few hours making thin section gauges that cracked in water/brine hardening .
I wasn't trying to be a "smart arse" but was trying to inform forum members that  quality gauge plate is quite a bit better than fairly plain high carbon steel  for critical applications. 
08/01/2011 18:48:02
"Gauge plate" is a much more refined alloy than Silver steel. Gauge plate is a lower carbon steel than Silver Steel and has the additions of Tungsten & Vanadium with a greater amount of Manganese to give a steel which can be oil hardened with much lower distortion and cracking and is much tougher in the hardened state. 
Thread: Rulers - my pet peeve
08/01/2011 18:28:29
Has anyone noticed that it's much easier to read a rule measurement if the division engraved lines are no more than 2 as long as the division interval ?
I've always found the 1/100th inch division lines too long and it makes it difficult to read but when division lines are are much shorter it's much easier to read .
Thread: MICROSOFT INTERNET EXPLORER 9 COMPATIBILTY WARNING
22/12/2010 20:14:38
Please note that the digital issues viewer will not work with the beta version of Microsoft Explorer 9.
I found this out by updating my Internet Explorer 8 to the latest version to see if the latest version would offer any benefits. I then discovered I couldn't access the digital issues images. Reverted back to version 8 and all is well !
Just thought I would try to minimise any unecessary head scratching and hair loss if other subscribers think of using Internet Explorer 9  ! 

Edited By Dinosaur Engineer on 22/12/2010 20:16:55

Thread: lathe belt
07/12/2010 16:00:42
Maybe the toothed belt is used due to a small pulley being used  ( high torque at small radius) and the pulley wheel centres are close so that it's difficult to provide enough "wrap around" for a 'V' belt. A friction belt would be better than a "geared" belt as it's more likely to slip rather than cause mechanical damage. The equivalent ' v ' belt drive would probably need more space and/or a tensioning roller to increase the small pulley "wrap around" 
Thread: Metric vs Imperial - Practical or Traditional?
06/12/2010 19:21:26
Hi ! Terry,
I've found that as soon as I get below M1.6  the price rises exponentially and trying to get  high tensile grade 8 or better, difficult.
The BA stockist you mention must be the same expensive shop I go to !
06/12/2010 16:24:25
There is no one system that provides all the answers or satisfies all the needs .Engineers will always find another solution ( system ) if one system doesn't offer what they want. Until such time that the metric system satisfies ALL needs, engineers will always find something else to do the job.
For the model engineer , the prices and availabilty in small quantities of minature metric screws ( incl. taps / dies etc) is a real problem . Also  metric scale hex sizes are not available. Is it it any wonder that we use B.A. threads / fasteners ( some times with non std. heads) ?
Thread: Brake Discs
04/12/2010 22:32:11
 
Stub Mandrel
I think the milled "notch" is done to balance the disc , not to provide a wear indicator .I've fitted many discs having this type of concave milling cutter notch.The ones I've seen would leave the disc dangerously thin if the disc was worn to this extent. Also I've seen these type of notches that were not centrally disposed across the width of the disc which leads me to think that they are purely for balancing. A quick check in the relevant Haynes manual will reveal the new & minimum wear limits for the disc thickness.
I would be very concerned for your welfare if you did not check this.

Edited By Dinosaur Engineer on 04/12/2010 22:32:32

Thread: lathe belt
04/12/2010 18:56:16
Maybe this post is a lesson for all of us to buy the more predictable spares that have a limited life with the M/C ?
I remember in the good old days that VW shipped Beetle spares to each country before they shiiped any cars .
Thread: Brake Discs
04/12/2010 18:23:04
I too remember the Japanese stainless steel/ iron brake disc fiasco in th the early 70's.They quickly changed to normal cast iron to resolve the problem but I think that for some time they have used some type of rust resisting iron/steel that doesn't seem to corrode.
I noticed in a fairly recent car mechanics magazine that it was mentioned that wear indicators were machined into the central preriphery of the vented discs . Some manufacturers do this as an aid to balancing. The only wear indicators I'm aware of on vehicle brake discs are machined into the braking surface of the disc . Once the braking disc area has worn away flush with the machined areas then the disc should be replaced. If wear indicators were to be machined in the disc periphery then this would be difficult to discern as this is the area of the disc that suffers most from corrosion.
 
Most car brake discs only have a 2mm wear allowance on the overall width before they must be changed . This leaves little material for "skimming"
 
It's unfortunate that quite a few current vehicle manufacturers seem to prioritise aesethetics over function to aid sales .My new car alloy wheel shiny "diamond finish"  coating is easily marked by auto washes . This never happened with the old silver colour paint. The use of steel fasteners in alumium alloy sub frames leads to corroded fasteners that are very difficult to remove without breakage.Most alloy wheels quickly corrode to the brake disc to make wheel removal difficult due to the inside wheel face being left as machined without any protective coating.
 
"Style over function" is the term that comes to mind.

Edited By Dinosaur Engineer on 04/12/2010 18:24:43

Edited By Dinosaur Engineer on 04/12/2010 18:32:37

Thread: Why is everything you buy such rubbish!!
07/11/2010 14:46:31
Pailo,
I too have this problem also . Bought some central heating radiators from one of the biggest DIY stores . The tapped holes were so far out of square that I couldn't make the connections to them . Had to exchange them 3 times before I got  reasonably square tapped holes. Ended up having to take a BSP tap to the store and to check/inspect before finding radiators suitable for the task.
Also bought  "reconditioned exchange" car brake calipers that were re-manufactured by the largest French OEM manufacturer and found various problems with them ( mostly leaks) . The worrying thing about these calipers were that they were not pressure tested as the tapped holes for the flexible hose connections were so full of crap that brand new hoses couldn't be fitted. After checking 5 calipers ended up going to another supplier. Even had to reject 1st one from this supplier ! And so the list goes on .
I think the basic reason for these poor quality goods is that the sellers do not accept any responsibilty for the quality and buy purely from a profit motive.Also the sellers have no technical knowledge or experience to judge / inspect ' fit for purpose' criteria.We urgently need toughened up consumer laws with penalties to stop this kind of thing.
Most worrying is that most people seem to accept these problems and work round them instead of getting the problems resolved . Where will it all end ? 
Thread: Surface Roughness Measurement
06/11/2010 15:17:32
If the surface finish spec was clearly on the drg. , why did the commercial M/C shop accept the job if they had no means of measuring/comparing it ?
Thread: Metric vs Imperial - Practical or Traditional?
03/11/2010 16:16:07
Chris Trice,
I'll bet you a £1,000 ( sterling) that the imperial system is still in use after your life time & mine.
Seriously though because of the legacy products that need support and also in specialised applications the imperial system will be used for far longer than you imagine . Most of industry changed over to the metric system some time ago but they still have to maintain & adhere to imperial standards that have been in use for many years if they want their products to be compatible with the existing user base.
Most PCs ( all ?) still have connectors with 4-40 UNC screw fittings and this is the industry that has adopted more changes over the years than most others .The imperial system is not just about measurements but also international standards.
I remember some Japanese test equiptment that was incompatible with international connection interfaces and the Japanese company had to change from their metric connector fasteners to the international imperial fixings .  

Edited By Dinosaur Engineer on 03/11/2010 16:47:50

Thread: TPI Threads
31/10/2010 22:22:35
If a design needs a reasonable strength thread in a fairly weak/soft material it's often necessary to use the old imperial thread systems rather than the standard metric threads. The standard metric coarse threads are fine for steel but are not sometimes strong enough in weaker materials . Many aircraft part threads are "Helicoiled" for this reason but this of course is more expensive.The coarser BSW & UNC are still often used commercially in metric designs . The hard disc example quoted in a previous quote is an example of this . The hard disc mounting tapped holes are still UNC threads in some discs to give adequate strength ( 8-32 if my memory is correct).
The mixup over similar size screws is not exclusively due to metric/ imperial mix . My English 40 year old lathe has 3/16" BSF and 2BA screws and it's quite easy to get them mixed up !
Thread: Metric vs Imperial - Practical or Traditional?
30/10/2010 13:58:29
As long as the older American planes are flying, there will be an imperial system which will be quite a few years yet and also camera makers will continue to use Whitworth tri-pod mounting holes in their cameras. I'm sure that there are many other imperial uses/users that will continue for a long time yet.
Thread: End mills in lathe chuck
18/10/2010 19:23:51
Derrick,
TIR or the more correct abbreviation T.I.R. is the total swing of an indicator . If for example a dial test indicator (D.T.I.)  is adjusted to read Zero on a perfect spindle which has no run-out then the T.I.R. will be zero.   If say the D.T.I. is set to read zero at one particular point on a piece of silver steel ( smooth round piece of steel) in the 3 jaw chuck , then the indcator may for example go to minus 0.003" at it's lowest point to say plus 0.002" at it's highest point for one full revolution . Thus the T.I.R. would be 0.005" which is the total indicator "swing". You may hear of eccentrics or eccentricity. Eccentricity is the amount the actual centre of say the piece of silver steel in the chuck, is from the true centre of  the spindle revolution. Thus the chuck at the gripping point of the silver steel diameter is said to be eccentric by an amount of 0.0025" . This is half the T.I.R.
Hope this helps

Edited By Dinosaur Engineer on 18/10/2010 19:40:36

Thread: Warco Gearhead Lathes
08/10/2010 16:17:12
Geared head M/Cs are invariably noisier than belt drive M/Cs.Most G/H lathes have spur gears which will "howl" at speed . For this reason most car gearboxes have helical gears in the critical areas but of course helical gears are more expensive.Even Helical gears will be noisier than belt drive.
<< First < Prev 1 2 3 4 5 6 7 8 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