Member postings for mick

I've used JB Weld before and it does give a very strong bond, the advertising says "don't bin it JB weld it" so I was hoping some one had put it to a real test. I fully intended to drill a series of small holes along both faces of the fracture to act as a key. Can't use the fixing plate as a jig, as it would obscure the area to be brazed/ welded. I'll give it a go over the weekend and see if it stands up to the advertising claims.

I've just bought an 1920/1930 bench shaper, which is in suprisingly good over all condition. About a third of the clapper box slide castings has snapped cleanly and has been repaired with a piece of bent sheet metal, with screws through to the broken and intact pieces of the casting, must have been repaired years ago as they used square headed screws. The fracture between the two pieces of casting is clean and the two pieces sit quite firmly together. My question is: has any one repaired a working casting with JB Weld and if so was the bond tough enough to be considered totally repaired. The only other option would be to braze the pieces together, but there is the chance of the parts moving during this process.

Good game this, here's my go

2 Tangental roller box

3 unsupported tool holder for chamfering etc.

4 Adjustable reamer holder

5 Looks like a tap holder

6 Die holder

Turning metric with imperial dials is really quite straight forward for everyday applications. Treat 0.040'' as 1.00mm. so by taking a one thou cut on the dials (two thou on the diameter) you should remove 0.025mm. So a 0.010'' cut will equal 0.25mm. 0.020'' = 0.5mm 0.030'' = 0.75mm. and so. I know it isn't correct to four place of decimals, but its near enough to get a turned diameter to size.

Could be wrong but they look like Myford one size spindle collets, if so they are tightened with a knurled ring that screws onto the spindle thread.

PB is designed to be a good hard wearing material, that's why its used for bearing bushes and the like. To be hard wearing it has to be very dense material and will be tough to machine. If you have a tool that's cut high carbon steel, like sliver steel that will be the one to use. Plenty of coolant will help, drop the revs, but don't cut back on the feed, as the tool needs to bite. If the tool isn't cutting then its in the process of becoming blunt as all its doing is rubbing. I know its expensive, but for a couple of quid more you could get free cutting bronze, which has all the bearing qualities of PB but is a joy to machine. Talk to Viv at Milton Keynes Metal, they advertise on the forum.

Wolfie has got close to your conversion problem, but to convert imperial to metric you must first express the fractions to four decimal places, so1/16th would equal 0.0625 1/32 0.0320 etc. All you do then is multiply the decimal by 25.4 which will give you the metric conversion. To convert metric to imperial divide by 25.4 25.4mm is equal to one inch.

All of the above plus, is the slide that isn't being used securely locked,, are you using coolant or cutting oil and are you climb milling

I'm trying not to criticise another's working memories, but production turners most likely did a 5 year apprenticeship and were working a heavy industrial ( and therefore more stable) machine. I don't think any turner that I've worked with and I've worked with some pretty tasty ones, could cut an 1'' Acme thread to a good standard of accuracy in four cuts. Acme threads are a precision thread used for such things as machine lead screws, where minimal play between the screw and nut is paramount, making it one of the most difficult threads to cut. A skilled turner, in my experience, would use two tools, a roughing tool and a finishing tool to produce the thread form. The roughing tool would cut a few thou below the root diameter, while the finishing tool would cut both flanks together, while not removing any material from the base of the thread, therefore avoiding any juddering which would effect the accuracy of the two flanks, and yes, I've cut my fair share of Acme and buttress threads. An Acme thread cut in four passes would, in my opinion, be only suitable for something like the screw for a sash cramp, where play between the screw and nut is desirable. To compare a hobby machinist to an industrial machinist is not a fair comparison, to a hobby machinist, time is not the over riding consideration, as he or she does it for the sheer pleasure and satisfaction of producing a machined component in his, or her spare time, a process that might be light years removed from his, or hers every day working life.

Goes some way to explaining why most of the old turners who were around when I was a lad had fingers and thumbs missing!

Martin.

As this is a beginners question I would be interested, purely for balance, to know which milling operations you feel would not be suitable for climb milling to be used and at what depth of cut climb milling wouldn't be the first choice for facing operations.

Well done wolfie, working in the dark you'll probably turn out to be a better engineer that the most of us.

Regards.

Mick.

This is why I was reluctant to post, as the original post mentioned cutter direction. The photo shows different areas cleaned up, rather than cleaning up the whole area in a continuous series of cuts, starting at the bottom left hand corner, looking at the machine. Then with only half the diameter of the cutting in contact, feed from left to right, until the bottom R/H corner is reached, then up to the top right hand corner with 50% cutter step over then, to top L/ H corner and back to the start, where the cutter is stepped over by 50% and the conventional milling pattern is repeated until the cutter reaches the centre. I've always understood this to be a conventional milling pattern. If the cutter was started at the bottom R/H corner and fed to the bottom L/H corner, this would be climb milling, as the cutter is trying to climb over the work piece, imagine yourself sitting on the cutter and look at the direction of cutter rotation, you should see what I mean. Feeding the cutter backwards and forwards is alright as long as you have the ability to correct any error in the Y axis, which on some hobby mills you can't. Any error in the Y axis would manifest itself as a series of small ridges in the direction of cut, which will only get bigger as the cutter diameter increases. That's why a spiral pattern will always clean up a face on any type of machine. I hope that clears things up a bit, so beginners will see the advantages. You can learn a lot from books, but when your teaching yourself, understanding the effects of climb and conventional milling, along with correct speed and feed for different materials and the importance of sharp cutters and coolant has to be the foundation.

Edited By mick on 02/08/2012 13:23:15

I've been a bit reluctant to post on this subject, as milling is such a complex topic, with everyone having their own theory, which I feel only goes to cloud the issue.

I know only too well what it feels like to be at the lower end of a complex learning curve, as I'm currently trying to master fishing with light rock tackle and my posts on fishing forums sometimes ask questions that turn out to be blindingly obvious.

Having looked at the photos the first thing to say is in order to produce a decent flat surface the cutter must be feed completely around the outside edges at a 50% step over and continue in this "conventinual" milling pattern at 50% step over untill the cutter reaches the centre of the job.

Next the cutter must be feed from left to right looking at the machine, this is known as conventinual milling.

To feed from right to left is known as climb milling, as you are in fact asking the cutter to climb over the work.

Lastly the choice of cutter. For this type of milling I would say sharp HSS milling cutters with coolant applied either by brush, or directed from an oil can are better. TicN coated cutters are designed to be used at high RPM and are ideal foruse on CNC machine tools and are not really suitable for use at low RPM.

I suspect I may have put the Puma amongst the Penguins here, but I feel this to be fundumental to the topic under discussion.

Edited By mick on 02/08/2012 09:34:25

Edited By mick on 02/08/2012 09:35:46

A four jaw in good condition will hold round and square section as true as you'l everl need for every day turning, if you want to turn hex bar it probably means your producing nuts and bolts, where the section can be tapped true in your old worn three jaw. I have a 4'' diameter TOS four jaw, which cost around the £75.0    I only really use my three jaw for holding turned parts in soft jaws.

Edited By mick on 31/07/2012 17:41:27

Why not get a small adjustable engineers try square, where you can set the distance required by using the head of the digital caliper, you should be able to scribe a line as close to size as makes no difference, certainly a lot closer than using odd legs.

On the 8th day the lord made the shaper and saw that it was good.

There is no finer machine to produce a completely flat surface and with a swan necked shearing tool taking off no more than 0.005'' it gets pretty close to surface grinding, with the advantage of staying completely flat when released from the vice, which is not always the case when the magnetic chuck is realeased!!!!

If anybody has a small bench shaper in need of a good home please let me know

there's a distinct chance that a 4mm drill will wander when drilling through 2'' MS Why not double drill using a 7.5 first and follow up with the 8mm which will give you a size and much cleaner hole

hacksaws are designed to cut on the forward stroke, where the frame is slightly lifted for the return, pull and push dosen't achieve much besides making your arms ache

A line from one of Clive James songs has always stayed with me "forty years of metal tends to get under your skin and the green cleansing jelly only goes to rub it in!"

I think the core drills your talking about are designed to produce a true round and size hole. Normal two fluted drills especialy larger diameter ones will pounce and chatter when enlarging a smaller pilot hole. A multi fluted core drill won't and so will produce a clean and size hole.