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Member postings for colin hawes

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

Thread: Material source needed
30/03/2016 16:58:28

Only a few days ago I made a hole saw from a roll pin to work on brass about 1/4" thick. I cut the teeth with a dremmel grinder by hand using a small grinding disk as accuracy is not important. It did the job much easier than I expected and was just as sharp when I finished.

Thread: How to cool a piece for a shrink fit?
22/03/2016 10:42:25

In my opinion you are unlikely to get a big enough temperature difference by freezing the shaft. I would expect a difference of at least 200 degrees C . Colin

Thread: Opening the gap...
15/03/2016 10:39:29

Quite right Michael, the gap piece should not be part of the structural strength, my old 7" centre height Drummond has a very usefull removable gap piece for doing bulky work on the faceplate and I've used it many times without problems on vintage car and motorbike repairs. Colin

15/03/2016 10:06:02

If no great care was taken to ensure good clean finish when originally fitted there is not much chance of the gap piece being accurate after removal and refitting. Some of the imported machinery I've used shows such carelessness in other areas and I suppose that's inevitable at the price. Colin

Thread: Tongue in cheek
25/02/2016 10:26:54

Interesting that the almost obsolete imperial system, being a binary progression, is more closely tied to digital computers and their components than the metric system replacing it is. Colin .

Thread: Boiler tests comercial or club
23/02/2016 17:45:25

My club (Mid Sussex) is £20 a year. We get a workshop and boiler testing for this. Colin

Thread: Vertex HV6 - Corrected Division Table plus universal dividing spreadsheet
23/02/2016 17:40:15

My Vertex dividing head chart (ratio 1:40) has a an error for 24t ,obviously a typo as it states 1 turn and 33/22 of a turn on a 33 hole dividing plate. You are going to spot the error though as it is impossible to do that. However, I no longer trust the printed charts without confirming the sums. Colin

Thread: The Workshop Progress Thread (2016)
16/02/2016 11:31:14

Now and then I do a bit more on the 1.5" scale Burrell I started years ago. I do bits of this in between other projects. No castings used on this model.

burrell model 3.jpg

Thread: Use of domestic room as a workshop
09/02/2016 14:13:18

You need to change shoes when you enter or leave the room to avoid swarf being carried around the house by them. Been there done that. Curly swarf can be very difficult to remove from some carpets. Colin

Thread: A question of Mandrels..
09/02/2016 14:06:25

It is best to make a press fit mandrel and turn the job between centres. Ready made mandrels for this type of work have a very small taper 0.002 on the diameter over 10" would be satisfactory. The taper allows easy fitting which gets tighter as it is pressed in.

Thread: How to turn an article partly covered by the chuck jaws
08/02/2016 18:45:43

To ensure concentricity I would do the bore first then put it on tight mandrel between centres to machine the ends and diameters. So the mandrel should be made first and can be used as a plug gauge. It's an advantage if the mandrel has a 0.002" reduced diameter for a short distance to give an indication that the bore is "nearly there" and to aid its press fit alignment. Colin

Thread: Removing bearing housing
04/02/2016 16:21:43

I would try heating it to around 200 deg C to see if that would release the bearing before using force on it. Colin

Thread: DC Motors Vs AC induction (single or three phase)
04/02/2016 13:14:05

A brushed DC motor tends to develop a higher starting torque against a load compared to a synchronous AC motor but has more components likely to eventually cause failure and it is also likely to be noisier. I once owned an old motor that seemed to combine the best characteristics of both types, starting as a brushed motor and changing to synchronous by means of a centrifugal device. I'm not quite sure how it did this but I think the centrifugal device lifted the brushes and shorted the armature windings. An induction motor is usually continuous rated, runs cooler and will go for decades without problems. That makes it very suitable for industrial machines. In my experience speed control of the motor is rarely essential. Colin

Thread: Time for a name change?
05/01/2016 16:48:35

If I had a CNC mill I would occasionally use it, not only because it can produce profiles that would require tedious effort to machine manually, but for it's ability to do so in 3D and also engraving. However , most of our models were originally made using manual machines and so CNC is not essential for those, but the satisfaction of seeing a CNC carrying out your carefully planned instructions is considerable and you can do your bench work while the machine gets on with it's work. Will I buy a CNC?.... no, because it takes too long to create the program for the sort of work I do and when I design something I ensure that it can be machined on what I have. Before I retired I used NC and then CNC machining centres for small batch runs and was happy to let the machine do the work. I still like to use my old manual machines just as much though .

Newcomers to engineering should note that old machines can produce excellent work; you don't need to spend a fortune on machinery for hobby use. Colin

Thread: Vice suggestions
27/12/2015 11:17:51

Low cost drill vices are not designed to take the side and lifting forces incurred when milling, you would be disappointed if you tried. The moving jaw on a machine vice needs long narrow guides. My photos show my homemade one that has been in use for more than eight years and it has features that you don't find on any other vice that I know of which are not obvious from the photo. Colin

Thread: DRO is driving me crazy.
27/12/2015 11:02:47

Is it possible that the reader is being strained by scale mounting errors? loosening both end clamps would prove this and my successful attempt to repair a reader a couple of years ago demonstrated it was very sensitive to any pressure applied to it. Colin

Thread: Merry Christmas to one and all!
24/12/2015 10:03:37

Enjoy your Christmas Neil and all you readers & families. Tonight is party night for me..... best wishes everybody Colin

Thread: Forging HSS?
20/12/2015 16:13:36

I have seen HSS forged and hardened by a factory blacksmith in a coke burning forge when I was an apprentice. He used to bend over the ends of boring bars for the toolroom. If I remember correctly these tools were "quenched" in compressed air. Colin

Thread: Gas bottles
09/12/2015 17:27:12

I wonder how good it would be running on gas and compressed air? Colin

Thread: testing on air
07/12/2015 11:38:24

I feed air in via a drain plug. Colin

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