What are you machining?

[Tigman]

Took the gap out again , had this shower plate on the Lathe, plumber set the shower in too deep , so by machining out the centre hole he managed to fit the plate ! Nice chrome finish on the plate so wrapped it in masking tape and set to it

 

[iNf]

This post is a mix of 3 different threads.
1st I bought this: https://www.mig-welding.co.uk/forum/threads/today-i-acquired.50192/page-2334#post-2404221
Then @Turbo posted this: https://www.mig-welding.co.uk/forum/threads/today-i-acquired.50192/page-2336#post-2406454
Oh bother said I, having not realised it was to short for a 4ft board and with a project coming up involving cutting multiple 8x4 sheets. So firing up CAD I ended up with this:

3d printing 2 of these, 1 for each end:

Resulting in a 235mm extension. Finally we get to some machining! Needing to extend the clamping rod as well, I found a suitable piece of 8mm bar and threaded the end 5mm. Then cleaned up and drilled and tapped the original rod, having to make a plug for the spindle and use low rpm as there was a lot of stick out:

Blending in the join:

Then cutting a new circlip groove:

Finally resulting in something that can clamp a 4ft sheet:

 

[Martin Hocking]

In attempt to fool myself that I do actually use my milling machine I’ve been fannying around making some clamps.

I rigged up the horizontal arbor to speed things up a little. Doing so has reminded me that when I’ve used it before I’ve usually ended up with an odd finish at the end of the cut. Can anyone tell me what causes this? Is it just the chips packing up at the end?

 

[Richiew]

Another keyway bush. This one is for a 16mm bore and a B type broach. The turning is pretty shoddy but I'm very happy with the slot that I cut on my Bridgeport.
A 6mm Aliexpress carbide endmill was used. They look suspiciously similar to the ones that Rennie tools sell. I think the font on the case sticker is the same although the branding is different.

I've managed a very nice fit that's much better than one of the slack offerings I bought off Ebay recently.

This was the mill going back in the case after I'd finished with it.

 

[Tigman]

Today I've been putting the edge prep on some plates for weld test , grinder first then onto the mill to get a finish , I tryed a few different ways but ended up dropping the head down , had to extend the head as far as it would go , the only problem is the quill was also fully extended , not great , I think this is because I have the height extension on the machine , take a look

 

[Richiew]

A pair of shouldered arbors or mandrels to hold gear blanks. I've been trying to practice some gear cutting on the Bridgeport to get familiar with it for a project. I tried using tapered arbors but found the blanks moved under the cutting forces. I think there's only 3 thou of interference on those type of arbors, and I'm using an 8dp cutter. I think the forces were too much. People demonstrate gear cutting on Youtube and often cut quite a delicate gear which I think is a bit of a con. The blanks were bored and reamed to size but I still had trouble. I did buy some medium strength Loctite to see if that might help but never got round to trying it.

The smaller one is one piece, En8 material. The larger one is En8 too but is two piece with a lump of plain mild steel welded on for the shoulder. They are both threaded M16 fine. The small one fits a 16mm bore. The larger fits a 25mm bored blank.

I did think about adding a keyway to prevent rotation but I'm the world's slowest machinist so thought I'd try and hurry the job along with what I had. Can always add one later.

The threads were die cut. The Bridgeport came in handy to keep the die square to the job.

Set up on the mill. Apologies for greasy camera phone. I'm cuttting to a depth of 6.85mm There is 10mm clearance to the washer clamping the blank down,

I last cut a similar gear (1.5 inch) on my smaller Marlow mill a couple of years ago. I didn't experience these problems then as I put the whole bar in the jaws of the dividing head and cut along it. The trouble with this solution is that it needs a lot of material to make clearance for the cutter at both ends and you do a lot of cutting which can promote wear on expensive cutters. Probably not a problem for aluminium but I want to do these cuts in steel. This is a pic from last time. I made three rather wide gears so there was actually little waste. I did attempt setting up again like this to cut a gear on the Bridgeport but the exterior surface of the ally bar is pretty rough and I couldn't get it set up accurately and indicated in. It wouldn't help me either as this setup wouldn't be useful for steel.

I'm cutting a 2" 16 tooth gear. The OD of the blank is 2 and a quarter inches. The 16 tooth gear turns out to be a nice, easy one to cut. The dividing head is geared 40 to 1, so there are exactly two and half turns to be made after each cut on the 20 hole plate. This means I am hitting the same two holes in the indexing plate, top and bottom each time. A bit of black felt tip helps if you mark them up. There was a lot of talking to myself as I counted the turns on the handle.

I made three revolutions with cut depths 2.4mm, 4.8mm and 6.85mm. 330 rpm. This pic below is the moment of truth cut with the last cut of the first rotation about to go in. Plenty of WD40 washed in. Success. The gear blank hasn't moved this time.

Bit deeper.

Final cut about to go in.

All the glitter brushed off.

Below is the final gear and the bar it was cut from. There's also a couple of mistakes from earlier showing too. I was tired and miscounted my turns on the partially cut blank. At least it was useful for trying out my keyway broach. The other gear with the dodgy spacing demonstrates my original problem. The measured intervals were a little too much and varied so there wasn't much left by the last cut. It seemed ok ish until then.

I had a little bit of trouble with the nut on the gear cutter arbour undoing itself a couple of times but I caught it in time. I think the gear cutter just followed the earlier cuts anyway as it came loose fairly late on. Something to get into the habit of checking in future. The nut on the home made arbor didn't budge. The thread is on the tight side. It is a lot easier and quicker cutting on the Bridgeport than the Marlow. I tested the gear against a spare gear cut on the Marlow and they rotate around each other fine. Close enough for government work and for what I need it to do.

 

[Richiew]

Been a brave little soldier today. Started off with some drama-free parting on steel. Used the full depth of the parting tool but had to finish it off with a hacksaw as the material diameter is 2.25 inch. I think the material is En1a bought off a fellow member a few years ago. Gave a terrible finish but drilled, bored and parted nicely. My parting has improved since I upped the rpms when parting. There was a discussion on here about it not too long back. I was in second from top speed, but on a Southbend that isn't really saying much.

Second bit of bravery. Cutting a steel gear on the mill. The stock material is much cheaper than ally but the cutters are expensive if I blunt them. I settled on 130 rpm. ( 4 x 100SFPM/ 3inch diameter cutter, roughly). Some guessing went on with regard to depth of cut taken on each pass. You can end up rubbing and blunting the cutter if you fanny about, apparently. I have blunted cutters in the past but my excuse then was I didn't have the horsepower to cut hard. The cut gets wider the deeper it goes so the effort required is not constant with depth, I think. Initially commenced with a 1.25mm cut but that seemed a little insipid so it was increased to 1.5mm. An oil emulsion cutting fluid is employed from a spray bottle.

This is the end of the second cut rotation. It was reading 3.3mm on the DRO if memory serves.

I got to indicated depth on the DRO after 5 cut rotations The last cut didn't seem right though. Stock removal was less than expected and the teeth looked too square and chunky. Not quite sure what went on here.

Took it off the mill to have a proper look and measure.

Compared with the ally one cut yesterday. Not saying that one is perfect either but the steel one is too square. The cut depth measured too shallow when compared.

The gears are slightly different widths and the ally one stands a few mm taller on end in this photo.

Not to worry. It was no bother to set it back up in the mill and take a few more cuts. The table height and Y axis were still locked, the x travel doesn't matter. The gear cutter was used to set the arbor back in the three jaw as the cut gear and cutter mate perfectly. I made a couple of test turns to check the cutter teeth and the gear lined up and finally fired the mill back up to take two further cut rotations to match the measured tooth depth of the ally gear. That's 112 cuts in total, it was a long afternoon.

The cut depth should be 6.85mm. The measured depth on the tooth taken with digital caliper was around 6.60mm. It's always going to be lower and a slight guestimate as the height is measured using the teeth either side as a shoulder to measure from. I couldn't measure from the top of the missing arc between the teeth. I think I'm fairly close. The ally gear was also used to check the tooth engagement, I made sure it rolled freely without getting stuck. Got there in the end, I think.

Steel top, Ally bottom. Going to make another steel one. It's only mild steel so there's scope to wear in nicely. I'm looking to make a stouter set of sheet metal rolls. Consequently, the gears will always be set a little further apart due to material between the rollers. This gives me wiggle room with regard to spur gear accuracy. Will see what occurs when I cut the next one.

 

[Agroshield]

The cut depth should be 6.85mm.

Looks good.

On coarser gears, you can pre-gash with a slitting saw or plain cutter or vee cutter (no wider than the gear root) so the involute cutter has an easier time.

There might be some deflection in your setup. On a more traditional horizontal mill gear cutting setup, you might put a support down to the bed (typical https://www.ebay.co.uk/itm/335348665486). You might be able to make a vertical equivalent, remembering that the point of contact would be different for a gear with even or odd teeth.

I wonder if filling the exposed threads of your arbor with a coupling nut so all of it until the tailstock engages it is fatter would make any noticable difference to its stiffness.

 

[Richiew]

Cheers Agroshield. I originally attempted to make the arbor with an M20 thread but the die cut went awry like last time I tried. We've been here before.

The gear cutting seemed to suffer on cut number five. Fatigue was setting in so the cut was set to the remaining depth needed rather than splitting it over two passes like it probably should have been.

The lesson seems to be more preparation and no shortcuts in future. I could probably shorten the threaded end of the arbor too.

 

[Martin Hocking]

View attachment 449789

A gear in the hand is worth two in the bush, well done richiew!

 

[Richiew]

A small follow up from yesterday.

Dug out my slitting saws. I bought these after the first time I cut some gears. JMS1972 on here suggested them at the time. They have been sat in a drawer for a couple of years. The written spec on the thicker saw made me laugh but I can't criticise as I cut DP gears with the DRO reading metric. Decided to try the 3 inch by 3 millimetre one.

Threaded part of the arbor reduced by half to help stiffen things up. There's still plenty of clearance, so no harm done.

Not much cutting done for a few reasons.

Firstly, the blank shown being cut was the third one that I'd attempted to make today. I overshot the bore on the first two and I can't be having a slack fit on the arbor. I spent far too long on the lathe.

The slitting saw is a very slow and horrible experience to be honest. I first attempted a 5mm cut and this turned out to be far too much, reduced the cut to 3mm and finally settled on 2mm. The arbor is much stiffer now. I spotted the obvious deflection today. Agroshield was certainly correct that I was getting this yesterday too. I didn't see it, but certainly felt it at the time.

The slitting saw really needs flood coolant to wash out the chips, the squirty bottle isn't up to it. It's a much more pleasurable and quicker cut using the gear cutter. I didn't expect to say that sentence. The bigger teeth on the gear cutter eject the chips no bother. The slitting saw costs about 8 quid from RDG and I managed to get a second gear cutter for 18 pounds delivered from Aliexpress. I'd rather take the hit on the cutter cost to be honest. Using the slitting saw made me wish for the first time that I'd got around to fitting the power feed on the mill.

I'll persevere with the slitting saw tomorrow to see if it gets any better. The run out on the slitting saw is quite noticeable too. I've learned a fair bit the last couple of days and I realise now it's probably most efficient to take less ambitious cuts with the gear cutter and get there at a steady rate. I suppose I'm having one of those days.

 

[minimutly]

Good luck with the slitting saw, I've broken all mine, teeth wedged in the job, cut through the drive key etc. All in all a bad expeience.

 

[Richiew]

They are pretty grotty aren't they? Wasn't sure if it was just me, it usually is. Worth a try though to experiment with. Maybe one with fewer teeth would be better? I'm not spending any more money to find out.

 

[Pete.]

M90 x 6mm pitch thread in a bit of manky inch plate. Hand ground 60 degree cutter from an old carbon tap.

M90 x 6mm thread

This is "M90 x 6mm thread" by Pete R on Vimeo, the home for high quality videos and the people who love them.

vimeo.com

 

[Brad93]

M90 x 6mm pitch thread in a bit of manky inch plate. Hand ground 60 degree cutter from an old carbon tap.

M90 x 6mm thread

This is "M90 x 6mm thread" by Pete R on Vimeo, the home for high quality videos and the people who love them.

vimeo.com

Are you using a dro to judge how much you wind back in? Just plunging straight in with the cross slide

 

[Pete.]

Are you using a dro to judge how much you wind back in? Just plunging straight in with the cross slide

No, the Monarch lathe has a threading stop. You wind it in to clear for the return pass then wind it out 2 turns to the stop and add the infeed on the compound. The only thing you need to think about is how much infeed to add according to the load on the cutter.

Normally I thread straight in but this 6mm pitch is getting on for all the lathe will cut so I took a 30 degree approach so it's only cutting on one flank.

 

[Brad93]

I see. Bloody clever things those monarchs

Dod you have a male thread to check the fitment?

 

[Pete.]

I see. Bloody clever things those monarchs

Dod you have a male thread to check the fitment?

Yes, I had 4" of M90 high tensile tie rod. This is the second one of these I have done the first was 120mm x 6mm pitch.

 

[minimutly]

M90 x 6mm pitch thread in a bit of manky inch plate. Hand ground 60 degree cutter from an old carbon tap.

M90 x 6mm thread

This is "M90 x 6mm thread" by Pete R on Vimeo, the home for high quality videos and the people who love them.

vimeo.com

Neat. what does the "infeed" on the return?
Sorry - read to the bottom...

 

[Tigman]

Treated myself to a 3 jaw chuck for the Chinese lathe , 250mm dia from RDG Tools
Came with 2 sets of jaws , very pleased with it , saves messing with the 4 jaw ! Got to find a hole for that now !