Here is a list of all the postings JDEng has made in our forums. Click on a thread name to jump to the thread.
|Thread: What machine tools are these?|
The blue grey item in the last couple of photographs is the main part of a Jones & Shipman X9 radius grinding attachment. This is designed to fit the J&S 310 or 310T tool and cutter grinder and is used to grind radii onto milling cutters. As supplied it comes with numerous fittings to allow the cutters to be mounted and set-up, these are not present in the photographs.
|Thread: Wohlhaupter UPA4 Boring and Facing Head Operation|
The coarse feed on mine locks in three places, each at 120 degrees. The detent appears to be at the bottom and the ball in this position is spring loaded, with the other two balls being loose when the key has been removed.
I had a quick look at mine when I got to work this morning. The coarse feed is graduated into three parts, each putting 0.080" on the diameter; total of 0.240" for one complete revolution of the dial. The fine feed puts 0.016" on the diameter in 0.0005" increments.
Inside the hexagon socket of the coarse feed there are three balls, about half way down. They are retained but loose, if that makes sense, and they are located at 120 degrees to each other in the vees between the flats. The two at the top (10 and 2 o'clock when the head is vertical) are loose but the bottom one is tight so I assume this is the one that does the locking; it locks up whenever one of the graduations is opposite the fixed line.
When the coarse feed is used it can be easily turned with the key in all the way but, when the key is pulled out half way the ball takes over and locks the dial once the next graduation is opposite the line. The fine feed dial then operates. The operation of either dial does not cause the other dial to turn although there is obviously a 15:1 ratio between them.
I have a UPA4 and have never experienced any major problems.
I am not too sure whether exactly what you mean in your post. Are you having problems with the auto feed for facing cuts, or does your problem lie with getting the fine feed screw to work when you attempt to put a cut on for boring or turning? If the latter, do you find the problem manifests itself after using the coarse feed screw? The reason I ask is because it is necessary, when withdrawing the Allen key from the coarse feed socket, to pull it out about half way - you can feel where because of a spring detent inside - and then to turn the coarse feed screw until it re-engages. I suspect failure to do this might cause the symptoms you are experiencing.
Apologies if I'm teaching grandmother to suck eggs.
|Thread: Endmill and Slot Drill grinding services in the uk|
I have only just seen this post. I advertise in Model Engineer and, amongst other engineering services, I offer a tool, cutter and drill grinding service. I might be able to help you out. Telephone number is 01430 - 424957.
|Thread: andrew barclay well tanks|
Keith's link says it all really.
For what it's worth, one of my customers bought me one in the mistaken belief he'd found a bargain at a boot sale. There seems to be a flood of them on the market and they're all the same plate; they seem a bit too thin to my way of thinking and cast iron doesn't seem to be the correct material. There are a lot of fake plates about at the moment, railway related and otherwise.
Most loco's seem to have brass worksplates although the later 1950's Barclays had aluminium - I have two of these, one on either side of a loco! The Railway Executive/BTC registration plates were usually cast iron as far as I am aware.
As far a
|Thread: Sharpening Fixture|
Have sent you a PM.
|Thread: SAR 25NC Project|
Have a look at Jim's website.
Very interesting and informative.
|Thread: Looking for engineers!|
Have sent you a pm.
|Thread: milling cutter regrind service|
Have sent you a PM.
|Thread: Dead centre vs. live centre|
I'm not being funny Norman when I say that I've never had a job that's worth losing an eye for either; or anything else come to that!
Safety has to come first.
I'd make sure first of all that the gasket material you have is correct for steam. Check with a company such as Heritage Steam Supplies; they specialise in this field and will advise you what is the best material for the job. Personally I can't see any harm in a soft gasket in this application but I would ask and be guided by the experts. They use soft gaskets around the top and bottom of Sentinel boilers and they operate at a far higher pressure than you will be concerned with.
I would use a graphite jointing compound such as Foliac (made by Rocol); smear it on both sides of the gasket. Personally I'd stear clear of Stag or Manganese paste, it sets like concrete whereas Foliac is fairly easily removed if you ever have to remake the joint.
Knock out the bolt/stud holes in the gasket before you knock or cut the edges to size; if you do it the other way round you may break the gasket.
Hope this helps.
|Thread: Taper Pin|
Imperial taper pins are tapered at 1 in 48; metric are 1 in 50.
|Thread: Rough Milling|
Just thought I'd stick my two pennorth in.
What speeds and feeds are you using? From memory Presto recommend a feed of about 0.003" per tooth when end milling; this equates to 0.012" per rev. For mild steel using a 1/2" cutter this means running at about 750 rpm with a feed rate of 9" per minute. If you reduce the feed rate there is a tendency for the cutter to "rub" which results in poor finish and premature failure of the cutting edge. Coolant is useful if you have it; helps chip flow over the cutting edge and flushes swarf away. If you reduce your rpm you still need to keep the feed at 0.003" per tooth.
Make sure all slides except the one you are actually moving are locked.
What type of steel is it? Some mild steel is extremely difficult to get a good finish on due to poor or indifferent quality control.
If you want to check for play in bearings etc use a clock gauge if possible. It will give a reliable reading from a known point which makes it easier to assess what is (or isn't!) going on.
These might be bridge reamers as stated above. If that is the case they are used to put a "sized" hole through two (or more) separate, smaller holes in components that require bolting or rivetting together. The idea is to "bridge" any misalignment.
They might also be taper pin drills; these are used, as the name suggests, for opening out a parallel hole to accept a taper pin. They will have a constant taper (1:48 or 1:50 depending on imperial or metric) whereas, as far as I know, a bridge reamer is tapered for a certain length and then becomes parallel.
Edited By JDEng on 09/07/2012 17:30:30
|Thread: crankshaft bearing material|
Try this company for white metal:
You need to make sure you get the correct grade though. White (or Babbitt) metal is an alloy of tin, lead, antimony and copper; the proportions determine it's melting point and its characteristics as a bearing metal. The more tin, the higher the melting point and the price.
You shouldn't really use second hand whitemetal, chiefly because of the risk of it being contaminated however there is also the need to know what grade it is and how it has been treated. If it has been over heated there is the possibility that it might have become "spoiled" which results in it becoming gritty and unfit for anything but scrap.
Whitemetal was used extensively for bearings during the steam age and is still used in some modern internal combustion engines today. It's a very good bearing metal and is vastly underated in my personal opinion.
|Thread: drifting in mid gear|
A mechanical lubricator should always be driven from a part of the motion which has a constant movement such as one of the main (as opposed to valve) crossheads or a part of the valve gear which does not alter its stroke length when the loco is notched up. Such a part is often one of the eccentric straps on a Stephenson fitted engine or one end of the expansion link or a return crank on a Walschaerts fitted loco.
If the lubricator is driven from any part of the valve gear which alters its stroke length as the loco is notched up then the amount of oil will reduce as the loco gets faster - a state of affairs which is not desirable!
If your engine's lubricator is driven from a component with a constant length of stroke then it doesn't matter whether you drift in mid or full gear, the oil delivery will remain unchanged.
|Thread: Using Micrometer/Hi-Spot blue|
I'm with you on this Keith. We were always taught to blue the face you weren't scraping because that's the standard you are working to. The blue is transferred to the high spots on the part you are scraping and you scrape to remove the blue. You shouldn't have to rub something that hard it squeezes the blue out or for that long it wears it away; you'd never make your bonus if you did!!
Scrapers should be honed with a fine slip stone on a regular basis; depending upon the material you are scraping they do sometimes lose their edge fairly quickly and then become more difficult to control.
|Thread: Machining what am I doing wrong?|
Hi Chris and Martin,
Martin: You are quite right in what you say about the equation I posted and in actual fact the simplified version is the one I use in the workshop "in my head" to work out RPM. I posted the full version because I feel it's important for people to be told the correct way of doing things; you can always take shortcuts later.
Chris: I don't entirely agree with what you say. High Speed Steel is a lot more forgiving than Tungsten Carbide and will tolerate a far wider range of cutting speeds and feeds. The recommended cutting speeds for HSS are designed to give the best compromise between production speed and length of time between regrinds; in other words they produce the optimum production/down time ratio. I totally accept that HSS can be run a lot more slowly without adversly affecting its performance although what is gained by this I'm not entirely sure. Drilling in particular is far easier if the correct speeds are used, the drill cuts more readily and less pressure is needed to feed the drill; if there's a problem with heat use a squeezy bottle full of coolant!
Tungsten Carbide on the other hand has been designed for use in a high speed production environment. It is far less tolerant of slow speed which is the point I was trying to make in my original post. If you use it below its designed cutting speed and feed the cutting edge will rub instead of cutting, this results in the cutting edge being worn away or failing prematurely which produces an extremely poor finish.
As a comparison it would probably be fair to say that HSS should be used at or below the RPM's calculated whereas TCT should be used at or above if a reasonable finish and tool life is to be expected.
I accept that most people don't need to work as fast in a home workshop as would be expected in industry however, if you are to achieve results with TCT then you have to work at the speeds it is designed for.
Cutting speeds are usually expressed in either feet/minute or metres/minute. This is an indication of how fast the tool tip should move over the work piece and is dependant upon the material being machined as well as the material which the tool is made from. To convert the linear speed to RPM we use the following formula:
RPM = Cutting Speed x 12
3.142 x diameter
where the diameter is expressed in inches and the cutting speed in feet/minute.
The formula is used for turning, milling or drilling however, if used for drills, the speed should be reduced to about 75% of the calculated figure.
Mild steel has a cutting speed of 100 feet/minute for HSS however, for TCT the speed is recommended as between 150 and 400 metres/minute (490 to 1310 feet/minute) - the lower figure for light roughing and the higher for general finishing. If we assume a piece of 2" dia bar then it will readily be seen that, using the formula, the RPM work out at 190 for HSS and between 935 and 2500 for TCT - a massive increase in speed.
For a piece of bar say 1/4" dia the speeds would be: 1527 for HSS and between 7485 and 20012 for TCT and this is where the problem lies. Most lathes cannot achieve such high speeds and therefore, in the smaller diameters, the finish suffers. In such a situation it makes more sense to use HSS.
TCT performs best when "worked" and that means using it as near as possible to the designed speeds and feeds and they are very fast. It is quite intimidating when you are not used to seeing the swarf coming off blue! Just as an example I was machining some EN24 yesterday, the bar was 2" diameter and I was running at 1850 RPM with a 0.010" feed and taking between 0.040" and 0.080" off the diameter on each cut (this was within the spec laid down for the tips); the finish, although slightly grooved because I was roughing the job for grinding, was like chrome.
The other things to be aware of are making sure that the whole set up is rigid with adequate support for both work and tooling. Coolant should be a flood or nothing; halfway house leads to premature failure due to stress cracks in the tool tip. I usually run it dry and then cool the job down with coolant before measuring if there is any concern over expansion.
TCT tips are very specific and it is important to select the correct grade for the work in hand and sometimes that means whether you are roughing or finishing as well as the type of material. Manufacturers do produce tables which detail the various feeds and depths of cut which specific tips cater for and again, it's important to work within these parameters if you want a good finish. With some tips it is not practical to take 0.005" finishing cuts; they are not designed to do it and the finish suffers.
TCT is a brilliant material but it is not a complete solution in itself and sometimes it is more practical and cost effective to use HSS.
I am not sure about the horsepower issue; I suspect that it would not be a problem provided the tips which are in use are designed for taking light cuts.
Hope this helps and I haven't gone on too much!
Edited By JDEng on 29/05/2011 19:12:38
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