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Member postings for Alan Charleston

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

Thread: Spot Facing With Slot Drill?
18/05/2020 07:19:23

Hi Ron,

I'm not clear as to how you milled the teeth. From your picture, I can see that the bottom of the cutter is in the same plane as the angled part of the tooth but the side of the cutter doesn't line up with the part of the tooth which is parallel to the drill. If the teeth were cut as shown, wouldn't you end up with a negative rake? Did you file the side of the tooth after milling to give a neutral rake?



Sorry Ron, I've looked at your post again and I see you say you filed the cutter after hardening to sort the rake out. I initially thought you meant you had filed the top of the teeth to provide clearance after milling the top of the teeth to ensure they were all the same height.


Edited By Alan Charleston on 18/05/2020 07:30:11

Thread: Insulating board that won't drop powder as it is touched
30/03/2020 06:44:54


I would agree with Dick that painting it with a solution of water glass (sodium silicate) would fix the problem. Years ago I made a small oven for use in a lab and it was insulated with a putty of powdered asbestos and sodium silicate solution. It was plastered on and dried by turning the oven on. The surface was stable and I used it for years.



Thread: Copper pipe Diameter Reduction
30/03/2020 06:37:00


I made a tool which bells out the ID of 1/2" copper pipe to the OD so two pieces can be brazed together. The small diameter is 1/2" followed by a slow taper till the OD is reached then a parallel length at the OD. The pipe is grasped in the left hand and the 1/2" section is inserted. The tool is then whacked with a big hammer until the desired result is achieved. It probably wouldn't hurt to anneal the copper first, although I haven't had any pipes crack.

Obviously the dimensions would be changed to suit your pipes.

Thread: Blueing (blacking) steel
15/02/2020 05:21:20


After a bit of thought I'm sorry I posted this. Even preparing the solution can be hazardous. Adding a kilo of caustic soda to a litre of water will result in a boiling solution which is extremely corrosive to skin, eyes and lungs if the vapour is inhaled.

"Not done it yet" is quite right about the PPE required. The gloves should be heavy duty gauntlet type and a full face visor is essential. No bare skin should be exposed. Both making up the solution and immersing the articles to be blued in the boiling solution should be done outside - not in the kitchen.

Probably best if the moderator deleted my post but I can't find out how to contact him.


14/02/2020 07:28:44


In the past there have been various threads about blueing or blacking steel, with people wanting recipes for doing it. Here is one I came across on Youtube.

The recipe is as follows:

" The recipe i used to make my gun black was:

This method is called hot bluing steel. First you have to boil water with washing soda and put all the parts in it to degrease the gun. Secondly take 1 kg POTASSIUM NITRATE (KNO3) and 1kg CAUSTIC SODA (NaOH) then mix both of them into 1 litter water and boil it. But make sure of your safety first. This is a highly exothermic reaction. So add ingredients slowly and mix them. Put all parts in the recipe then let it boil till you get your desired blue-black color. Apply oil to the parts. "

He shows the process about 8 minutes into the video.

I'm not sure how easy it would be to source potassium nitrate these days ( I got 500g from the local chemist when I was a kid 50 years ago after swearing I wasn't going to make gunpowder - yeah right) and of course be careful when adding the caustic soda to the water (gloves and glasses.



Thread: Delays in Shipping from China
07/02/2020 05:46:37


I ordered some carbide milling cutters from China through AliExpress on the 16th January and I see that they haven't been shipped yet. Normally this happens within a few days of the order being placed. Given the situation in China I'm not complaining - I feel really sorry for them.

Have any others seen this? I don't know how businesses over there are run, but if western companies had to suddenly shut down for weeks at a time, there would be mass closures I imagine.



Thread: Where to acquire a small amount of bromine
07/02/2020 04:50:42

Hi Ian,

I used to use bromine in a lab. Mark and Dave are right about using and storing it in a fume hood - it's nasty stuff. Although the boiling point is 59C, it has an appreciable vapour pressure at room temperature and gives off brown fumes which are as toxic as chlorine which was the first poisonous gas used during the First World War and has been used in Syria. I would suggest that unless you've had more than just secondary school training in chemistry that you give it a miss.



Thread: At last - no more chattering when parting off!
07/10/2019 08:11:25


Came across this solution to chattering when parting off on youtube.

Go to 58:26



Thread: Glass cutting
27/08/2019 07:04:51

Hi Ken,

I'm not sure using a cut down bottle is such a good idea. Bottles are usually made from soda lime glass which doesn't handle thermal shock well. The glass will get hot from the lamp flame and if a bit of water gets onto it it will likely shatter.

You would be better off getting in touch with a scientific glassblower who should be able to supply you with a length of borosilicate (pyrex) glass of the right diameter and with the ends flame polished to take away the sharp corners.

Mind you, I thought miners lamps had copper or brass gauze around them to prevent methane in the mine atmosphere from igniting.


Alan C.

Thread: Dehumidifier project
30/07/2019 07:02:00


I assume you want to dehumidify the atmosphere around your machines to prevent condensation and corrosion. If that is the case all you need do is to raise the temperature a few degrees hotter than the surrounding air to keep the relative humidity less tan 100%.

I used to run a steam generator which was sometimes hard to start due to condensation in the electrical control gear. I fixed it by putting a heated towel rail on the ground underneath it. It didn't take much electricity to run, was designed to run continuously and stopped water from condensing on the generator.



Thread: Guess the Chemical?
28/07/2019 06:53:20



Thread: Threading Problems on Colchester Student
18/06/2019 10:02:29


The idea isn't mine. I picked it up from this YouTube video.

He shows how to do it very clearly. I've used it on a bunch of different threads and it's never failed.

I think the reason it works is that by engaging the half nut on the same thread dial number when reversing, it engages on the screw at the same point as when it disengaged going forward i.e. it's the same as not disengaging the nut but stopping and reversing the lathe.



18/06/2019 07:22:06

Hi Stephen,

You don't need to keep the half nut engaged when cutting a metric thread on an imperial lathe if you have a thread dial fitted. The procedure to follow is:

After setting the tool to cut the correct depth, start the lathe in the forward direction and when the thread dial reads 1, engage the thread nut.

When the tool has advanced to the end of the thread, disengage the half nut and turn the motor off.

Withdraw the tool to clear the work.

Start the lathe in reverse and when the thread dial reads 1 engage the half nut.

Run the lathe in reverse until the tool clears the work.

Turn the lathe off but leave the half nut engaged.

Set the tool to the new depth and start the lathe in the forward direction.

Repeat till the thread is cut to size.

This method is useful because disengaging the half nut stops the tool a lot quicker than waiting for the lathe to run down giving a more accurate stopping point.

I don't know if it makes much difference, but the half nut on my lathe also has a bit of play in it and I always grasp the apron handle when starting a cut to apply a bit of force resisting the movement of the saddle and making sure any backlash is taken out of the half nut - don't get too enthusiastic though, a gentle pressure is what I aim for.



Thread: Quicksilver
05/06/2019 07:29:27


Clive is quite right about using nitric acid to clean mercury. I used to use it in a lab to determine the bulk density of porous fertiliser granules by measuring the force required to submerge them in a pool of mercury. The mercury required frequent cleaning and this was done in two stages.

The first one involved setting up a filter paper in a funnel and piercing a small hole in the bottom. The dirty mercury was put in the top and the mercury went through the hole while the foreign bits and some of the oxide was left on the filter.

The semi cleaned mercury was then put in the bottom of a Buchner flask and covered with dilute nitric acid. A bung fitted with a length of glass tubing was put in the top of the flask such that the end of the glass tubing was below the mercury. A vacuum was then applied to the side arm of the Buchner flask and air drawn through the mercury. Initially it just slopped from side to side but when the mercury was clean, it separated into a myriad of beads.

Most of the dilute nitric acid was decanted off (down the drain - this was 50 years ago) distilled water added and the process repeated 3 - 4 times to clear the rest of the acid from the mercury.

After decanting off as much of the water as possible the mercury was then dried by blotting it with filter paper. It came out bright and shiny.

We also used sulphur on mercury spills - the idea being to convert volatile elemental mercury to a non-volatile sulphide.



Thread: Boxford Screwcutting box / Leadscrew binding
14/03/2019 05:17:28

Hi Andrew,

If you want to get the gearbox off you'll need to slacken off the bolts holding the headstock in place and slide it forward which will reveal the cap screws holding the gearbox in place.

This is not easy as the front bolt holding the headstock down is really awkward to get at and there's very little room to swing a spanner between the sides of the bed. I ended up buying a good quality 15mm ratchet ring spanner to get it out. Due to the restricted swing available, it needs to have a fine ratchet action so a cheap one won't do.



Thread: Machining cork!
05/03/2019 05:02:07

Hi Maurice,

Moulding a silicone bung sounds a good idea. If that doesn't work try a scientific supply company. Rubber bungs are made from a small end diameter of a millimeter or so to huge (>100mm).



Thread: metal spinning small bells
23/02/2019 05:24:07

Hi David,

You may have a problem trying to spin a bell. Whenever I've tried spinning brass I've found I need to keep annealing it to get it to flow evenly. I suspect annealed brass will be fairly dead as far as ringing goes so you are more likely to get something to ring by turning it from either a hard brass or bronze. Phosphor bronze may be a good candidate as it is hard and readily available in short lengths for bushings.

I actually have some brass which rings really well. It is 1" dia. and came from an old set of door chimes. Two different lengths were suspended from wooden plugs driven into the ends of them and a solenoid mounted between them hit first one then the other with a wooden striker giving a ding - dong noise. You might find some of this material in a junk shop.



Thread: Quality issues with a SIEG SX2.7 mini mill
20/02/2019 05:43:53


I have an SX2.7 mill and it has a peculiarity I'm not sure is a fault or not.

If there is a drill in the chuck but the mill is not turned on, and the quill is lowered using the handle on the right until the drill hits the work, it is possible to continue turning the handle a bit (say 2 degrees) until it comes to a hard stop. It's like the rack and pinion is really loose and a spring is used to keep the pinion at one end of the rack on the quill. This results in a tendency for the drill to suddenly drop a bit when the pressure comes off and grab when it breaks through the bottom of a hole. Is this normal. I did try to pull it apart to see if I could see what is wrong (if anything) but with the electrics in the handle to enable power tapping (a truly useless complication) I chickened out half way through and put it back together while I still could.

When I first got the mill, it came without the little bit of brass between the locking screw and the quill so I couldn't use it as a mill. The local supplier got onto Seig and as the part only weighed a few grams I expected them to mail the bit. No - they waited until they had a container full for the supplier - so it was about 3 months before I got it.

The other problem with the mill is the lack of oiling points. Unlike the SC4 lathe I was silly enough to buy which seems to have had a shotgun involved in the decision where to put the oilers, the SX2.7 only has one oiler - on the bushing end of the x axis screw for the table. It's really awkward trying to get the ways a screws lubricated.



Thread: Anyone fitted a DRO to Sieg SC4?
10/02/2019 05:08:38

Hi Jim,

Rather than fit a DRO you may want to consider making a bracket to screw on the rear of the carriage and a DTI. DTIs are quite cheap through AliExpress and seem to be accurate.





Thread: Filing A Curve
28/01/2019 06:47:43


I was watching the video posted by Jason of the guy making a ring from a couple of brass nuts. I noticed he was filing the ring by starting with his left hand high, and following the curve with his left hand dropping as he pushed forward. This seems to be the usual procedure for most if not all of the people I see filing curves which is not surprising as it is the natural way of doing it.

When I was taught workshop practice at the Tech however, the tutor went to a lot of trouble to stop the class doing it that way. He taught us to start a cut with the left hand low, and to raise it as the file was pushed forward. There was a lot of muttering about it initially, but once the technique was mastered, it seemed to give better results, although this may have been because we were getting a lot of practice in filing.

Is the way I was taught the "correct" way or doesn't it matter which way it is done. The guy making the ring certainly ended up with a nice curve.



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