Member postings for Justin Thyme

it is a wedge shape, so 0.5 off one end and 2.5 off the other. at 0.2mm it seems to cut with consummate ease. at 0.3mm there seemed to be a bit of viabration, it all seemed a little less happy.

What about depth of cut? I used 0.2mm for each pass, is this about right?

And on the subject of depth, this machine does not seem to give any real means of adjust depth accurately - hence the print out and dial that I have stuck on the end

I think it is a tungstan carbide cutter, but will check    (how would I know, I don't see how all those flutes could be?)

Yes the quill is locked. but I was not locking the x axis hen moving the Y. would that make a difference ?

not sure waht you mean about ridges between the lines - it is mainly visual, although I can feel a roughness with my fingernail.

Edited By Justin Thyme on 20/09/2023 09:36:41

Could anyone offer some advice on how to improve the finish, it isn't too rough, you couldn't peel tatties with it but I would have hoped for a better finish (i still thing it will polish up ok with some wet and dry)

speed 2000 rpm, 10mm 4 flute, used cutting oil.

Is it the same or simlliar to what used to be known as Concrete Cancer? The steel reinforcement within the concrete rusts and expands thus destroying the cement, so I would guess it can't really be stabilised.

It does doesn't it. However I guess they only need to hold it loosely in place for the first few dozen fathoms, after that they are surplus to requirements.

That is about the same number of people killed on the UK roads every day, and that rarely if ever makes the news. And most of those who die venturing onto our roads did not believe they were taking any risk, often killed by others breaking the law.

The folk on this submersible were on a great adventure knowingly doing something phenomenally dangerous. I take my hat off to them for their spirit of adventure, but should we feel more sadness than we do for all the other deaths As usual the media is sweeping us along, controlling what we think and what we should be sad about.

with the thought that carbide is brittle and can shatter. Would it be safer to at least start this 'interrupted' cut with a HSS bit ?

Since I'm going to do this job now, I will use a HSS bit (if they fit the tool holder) , but be interested in your thoughts if this is a valid concern

Ooop's, yes I seem to have omitted that important spec..

I did mark out all the three circles before I started. The problem arose when I used the pillar drill to bore the centre hole out with the hole saw, the pillar drill is so unconcentric it managed to get the not very round hole in the wrong place. See my first image, you can see the scored line .

Never mind, I managed to mount it on the milling machine, and with an edge finder on the inside of the hole I worked out where the centre would be. from here it was very straight forward to get the holes drilled accurately (within a few thou, I quite surprised myself)

I was then able to score a line to where the outer edge will be. From there I have hacksawed and angle grinded it down to a roundish shape.

I'm going to have a good think about how I will lathe this down to its 89mm dia - it's non-roundness is a concern. What speed should I start with? When doing such things turning wood I will keep the speed very low until it gets fairly round. Will I use the same tactic on steel ?

I did spin it and felt 100-150 rpm seemed OK, not sure though

I could get a 3rd bolt in to hold the plated together, should I bother, it seems very secure

Yes Nicholas, that is exactly what I was going to do, there would have been plenty room with the cross slide off, but I would have need to form a bit of plywood to protect the base from dirt, fillings etc, then would I need to readjust the gibs when reassembling, seemed like a lot of work , so did'nt bother. But it certainly could have been done if it was important, and this isn't.

Anyway, moving on.

I now have the two squarish plates with a 39mm hole in the middle. I now need to create an outer edge of 89mm dia concentric to the inner hole, and also 4 evenly spaced 8mm holes 35mm from the center.as per this 3d printed one

The plan is to mount it into the chuck as per JasonB's earlier picture

My plan is to then score two circular marks, one with a dia of 70 and the other 89mm.

The 70 mm dia line will allow me to mark out and drill the four 8mm holes

and the 89 mm dia line will be a guide to cut and grind down to before remounting the piece in the chuck and precisely turning it down to 89mm

But how do I accurately measure the two circles, how will I work out where the exact centre is? The smaller lathe has a digital readout, but how do I zero this? Should I start off with another piece of round bar and establish a zero point off that - or do I simply score a ine at say roughly 95mm, then if that measures manually at 94.7 would I use that as a ref and work from there.

There is room on the chuck, so do I turn them at the same time ? should I hot melt glue them together, or may if there is enough room, drill the holes first and bolt them together. ?

Aye, but I needed to create the hole in the plate first, I was wishing to do this on the lathe. I had wanted an excuse to use the 4 jaw chuck.

Now the hole is created (on the pillar drill) I can move on to the three jaw chuck to form the outer edge. (and yes I can soon get it into reasonable roundness with the angle-grinder before machining on the lathe

As for downloading books, I got a box full of books along with the lathes, I find books hard going for some things. and was hoping to ask things not easily found in reference books on here. For instance, as I asked earlier, would removing the cross slide so as to do a job be a common practice. I didn't think it worth the time and effort for this job, but would that be something others would consider or would it be a big No No.

Indeed it was two 3mm plates. In what way could it be dangerous, it seemed very secure.

I'm sure I would be soon aware if there was any looseness, and once the hole saw was engaged then the work piece would be trapped between chuck and tail stock ?

Yes it was too small for the outer jaws, packing would have seemed a bit precarious.

As for the centring of the hole, this, by luck was not necessary, however I was curious if I could have centred it, had I need to enlarge or improve the hole - something I may need to do in the future.

Yes, but they don't take square bits, and even if I rounded the outside first they would not be big enough.

Got a start on it today, as ever, it didn't quite go according to plan. As you can see the slide thing (whats it called?) was in the way and too big to go under the chuck, and this meant that I could not get the tailstock any where near the work piece. I could have removed the top part of the slide thing so as to get it under the chuck, but it seemed like a lot of effort. What should I have done ?

So what I did do was drill out the centre holes on the pillar drill, here I was very luck, the hole saw is supposed to be 36mm, but our hideous pillar drill is so unconcenteric (is that a word) that the hole turned out to be very nearly 39mm, a little bit of work with a file and it was perfect.

The other prob that I encountered (and I'm hoping for a bit of advise) I tried to put the plate after the 39mm hole was created, but just could not get it centred, I have one of those dial things for checking concentricity, but couldn't set it up on the inside of the hole.

I used to smoke heavily when working with asbestos, (the monkey dung variety), I guess the asbestos would not have become more dangerous after passing through the red glow of the fag end - LOL

Edited By Justin Thyme on 17/06/2023 20:08:00

I have no idea where the insert come from (other than it was in with the lathe stuff) and the bright steel is an off cut from a local fabricator. (I only do free stuff)

I will get the speed, cut depth etc (inc some pics of the carbide bit, angle of attack) later today. then may be you could advise on how to do it better. I'm utterly cluelss in what I'm doing, guess work. (but all the same, what I made will work well, so I'm well chuffed)

Just reviving this old thread. First real go at using the lathe (at least first time making something for purpose) And was a bit disappoint at the smoke it was creating, seems pretty obvious it would be unwise to be breathing this stuff in, although I did today. I was cutting back 70mm from the end of a bit of 20mm dia bright steel bar to 15mm. I was told to apply a dab of cutting oil to the surface before each cut. It was fair smoking, The cutting could be described a bluish spirals.

I may be should have worn my forced ventilation ffp2 helmet that I use for wood tuning, (not sure if ffp2 is useful against smoke?) Creating ventilation could be a problem (unless I start using it a lot)

However I read this thread with great interest - as I was using a carbide cutter (or at least I think I was, brass coloured diamond shpaed bit), may be I need not have used any cutting oil (or may be just some for the final cut)

So to my question - Is it fairly agreed that not using any cutting oil is OK when using a carbide or tungstan Carbide bit on mild steel ?

and here it is (a new axle for a sack barrow) quite proud of it.

Just asked Bard & Chat GPT for 36mm bi metal hole saw speed in mild steel. Bard suggests 500-700 and . GPT goes for 150-200.

An internet search suggests to me 250-300

so I will need real people on an engineering forum to tell me the facts, who will also be able to add some other useful tips and not obsess about safety glasses.

it is isn't it. can make so many clever little things that otherwise would never be attempted. Just from this weekend, we need to add a vent to a machine, so was able to make a 6" to 4" connector and a little bracket to hold the 4 inch pipe to the wall.