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Member postings for HOWARDT

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

Thread: Lifetime of Commercial Tooling Vs. Home-made
17/04/2016 17:44:14

Still got most of the pieces I made in the late sixties at apprentice school, LETG, at Hinckley College as was then. The most used a 12 inch long screwdriver, silver steel shank with heavy steel milled handle. Not re-worked the flat end in all this time and it's the one I go for to remove stubborn screws.

Howard

Thread: Short morse taper drill bits.
14/04/2016 23:19:07

We used to use split morse taper holders with tangled drill of the required length. Expensive as tang sizes change as drill sizes increase so require a number of sleeves. Cheaper to use collet holder or simple chuck.

Howard

Thread: Linear Brearing Quality?
14/04/2016 10:06:08

i have used Igus bearings a lot in the past on both low speed and high speed reciprocating and rotating designs, they are very good. Make sure you look through the catalogue at the material options and choose the one that fits your criteria. They are very helpful, so maybe look and get an idea of the required criteria and your possible choice, then give them a ring.

Hope this helps.

Howard

Thread: Desoutter 36volt Power Supply
08/04/2016 13:40:55

Try looking for a local Desoutter agent, used to use these on production machines in the past and the U.K supplier was always helpful.

Thread: Mini-lathe question
28/03/2016 19:35:14

There should be some deflection of the belt mid way between the pulleys. The amount depends on the belt type, it's width, centre distance and pulley sizes. Look at manufacturers information, Gates is a big manufacturer and covers most belt types.

Howard

Thread: Price of steel
28/03/2016 11:17:50

I remember a number of years ago, probably about twenty, when it became necessary to buy steel by the tonne rather than the length just to be able to get it from the stockist.

Now with all the steel coming from abroad it makes you wonder how much longer we will be able to afford an engineering hobby.

Howard

Thread: More help required
27/03/2016 13:01:36

Slideways would be ground and then scrapped in the past, but that would be on high use machines. Scrapeing was used to break the surface and remove high spots, this also created pockets of for oil. Lapping is of no benefit as you would create too smooth a surface which means oil would wipe off and not go between the surfaces.

I have a new C3, just started retirement hobby, and have done nothing to it other than turn steel. As a life long machine tool designer I will use it until I find something wrong rather than look for errors. I have clocked it to see how true everything was and that is all.

Howard

Thread: piston rings vs. silicone o-ring
26/03/2016 16:35:33

Backup rings are used when the radial gap allows the pressure exerted to extrude the ring into the gap. I would not use an o ring in a piston that crossed a port or was used in any thing other than an oil system. There are many special shape and material seals for use in non oil based systems but need to be matched to both media and pressure. Trelleborg sealing systems have plenty of information on their web site if you need to get more confused!!

Howard

Thread: Snapping taps
23/03/2016 14:07:23

In industry theoretical calculations are based on using the standards for the fixings, i.e. unless the fixings are to the standards then the calculations do not apply. Also any additions specified such as lubrication. Where strength is critical then the fixing standards have to be specified for purchase and may include testing requirements. All this is a little OTT for the model engineer. We have to accept what we get, and in most cases it doesn't matter that the fixings are from some unknown source. As John said trying to get fixings to specified standards is not easy as the market is flooded with cheap imports with no traceability to source. I will stick to 1 to 1 1/2.

Howard

23/03/2016 09:40:07

As Martin has said there is no need to tap to deeply. There is a lot of information out there on calculated strength of threads. You only have to look at the thickness of a standard nut. The nut thickness takes into account a chamfer each end of the hole and a given number of full threads. I was always told that in steel you have the depth of full thread equal to the diameter and one and a half times for aluminium. Always chamfer the hole to allow for the radius under the screw head and to remove the burr raised during tapping. The blind hole depth depends on the type of tap used, if you are hand tapping with a bottom tap you can obviously get closer to the bottom of the hole than machine tapping. Have a look at Emuge tap catalogue there is lots of information which may help to analyse what your particular taps are capable of.

Howard.

Thread: MacBook Proo access to digital magazine
18/03/2016 20:45:36

I use Mac in all forms and use PocketMags to down load, also read through this website. Just wait as Dave said for your subscriber number, I had to ask for mine as it was not forthcoming.

Thread: check valves
14/03/2016 15:28:30

Roundness of the hole doesn't matter that much if the ball is struck to leave a complete circle of indentation. The hole is only an outlet and allows the ball to be positioned. Using a slot drill or end mill will not leave a flat face unless the cutter is well ground and the spindle is square to the part.

13/03/2016 09:29:01

Years ago I used to make a high pressure ball valve, 2500psi, with a stainless ball in a brass fitting. We used to place a ball on the hole and strike it once, then build it with a new ball. Worked every time. That ball was around 5mm in diameter. On another assembly we used carbide seats and glass balls, 750 to 1500psi. These had to work out of the packet, you can't deform glass or carbide 😀😀.

Thread: What Did You Do Today (2016)
12/03/2016 21:14:53

Not today but the last week. Finally made the jump and bought a Sieg C3 lathe and Sx2 mill. Looked at various options but being close to a supplier helped in the choice. Buying both together got me a fair deal on a good selection of tooling to go with them.

My reason for choices was I am only using the machines for hobby use, intend to build gauge 1 and 3 1/2" locos. Also my engineering workshop has to fit into a built in garage, in the UK these only accommodate a micro car not the F150 in an American garage.

So far I have only bolted the machines down and ensured they worked, my next project is to check both machines for accuracy. Have both 80mm Chinese chuck and ER25 collet chuck so it will be interesting to compare these as bought. Will have to get some bar before getting the lathe fully tested along with some of their tooling.

Thread: Does round plastic drive belt warp?
06/03/2016 19:58:56

Shape that is formed by an non tensioned belt makes no difference to its performance when tensioned. Stockists often hang belts from a single point so will form oval while hanging in stock. So long as the belt has not perished and gone hard it should function well enough. Round belting is used for low torque applications.

Thread: Imperial Drawbar for a Metric BF20 Mill
04/03/2016 11:59:33

Why not just pin a nut, or special end onto some studding. Simpler and no long turning problems.

Thread: Materials suitable for coolant.
02/03/2016 14:02:57

In a hobby environment I question wether you would want to get into flood coolant. I remember when we used to clean machine systems out and the awful mess. As Dave said in his note they can go off and produce an awful smell as well as being a bio hazard. I have known instances of leaving a machine over the weekend to come back to hundreds of litres of rancid coolant. That required the expense of a tanker to dispose of it and a day cleaning everything out. Oh happy days!

Cheers all

Howard

02/03/2016 12:37:35

You need to get an engineers reference book. I have one from Cromwell tools, a give away, from some years ago. Inside these are all sorts of engineers cutting information, including speeds and feed and coolant requirements.

Things have changed some over the years with synthetic coolants and tool coatings. So try to use upto date references, not something that was said in the 50's.

At the end of the day the best way to learn is research, and find what suits your equipment. Remember that a lot of people may refer to industrial size machines which will produce very different results to a hobby size machine. Having said all that for most situations in hobby machining an aerosol cutting lubricant or non is all that is needed as the cuts are light and short.

Thread: Deciphering the carbide tip code?
15/02/2016 21:22:52

Go to a tool manufacturers sight such as Sandvik, all code breakdowns are there.

Thread: How to gently increasing pulley bore size
11/02/2016 10:44:28

Flex Hones design will not produce a cone as the constant movement through the hole and the design of the hone prevents it. Any diameter/length ratios are permissible.

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