A common fault among the hard of thinking.

While trying to machine the back face of some poppet valves yesterday I suffered some unusual breakage of my carbide inserts. They would shatter, but in a laminar manner, coming apart almost like shaley slate. I tried various tool angles, speeds, and kept breaking inserts. I can usually get many hours of use out of an insert and suddenly this was beginning to look like an expensive exercise.

You've probably guessed what the issue was. Once I restarted the lathe in the right direction it all worked fine.... what had further confused me was the machining I had done immediately before this was using an HSS tool and it cut fine.... it's worrying I didn't even notice it was in reverse, especially with a myford chuck being a screw thread!

Just one of those days.... please tell me I'm not the only one....

You're not the only one.

Feel better now? Of course not, because, deep down, you know it will only get worse. Welcome to the club...

No Jon, you are not the only one. Doesn't happen with my inverter driven lathe as I have programmed it to start slowly so I can see which way the work rotates.

Thor

Never done it on my lathe (yet!), but have cream crackered a cutter on the Centec mill. My fault, of course, as I had fitted the mill with a 3 phase motor (to replace the single phase item) and broke it before I changed the normal motor direction to default for the vertical head, at first switch-on. The motor needs changing direction between vertical and horizontal modes on this mill.

I may get the direction wrong when milling horizontally, but that always needs thinking about and the cutter only turns slowly, when using the arbor and support, so the cutter has never been fed into the work in the wrong direction - yet.

I expect it will happen one day, but the 3 phase slow-start certainly helps. Another reason why I don’t like reversing drive possibilities with single phase motors…

I dreaded doing this from day one, so as our Chester lathe and Sieg mill both have the same rotary rev-off-fwd switches I printed a little stopper. It fits tightly to the sides of the square switch bezel, but can be slid up and down to prevent the switch being put into reverse without first moving the stopper. It has worked so far (touch wood). I haven't got access to the machines right now so cannot take a photo, so here is a render of the STL.

Brian G

(Edit: In case it is any use to others, I just posted it to Thingiverse as Reverse Lockout for Chinese Lathe )

Edited By Brian G on 06/07/2022 10:40:22

Hi Jon,

For what it is worth it happens to the best of us.

When I recently completed the Screwcutting Clutch for the Emco Compact 5 and switched it on for the first time. I was filled with blind panic. Moving the operating lever to the left sent the carriage to the right. That's not right I thought, what have I done wrong.

Switching the lathe back on it worked perfectly, then the light came on, Holmer Simpson comes to mind, DOH.

My only advice is not to worry about a single incident, be more concerned about repeated events.

Regards

Gray,

I have the switch go towards the tail stock for on forwards, and towards the gears for reverse. A friend asked why this was important. I said for when thread cutting, you really want to know the direction without needing to look at things.

I blame it on a senior moment in my shop.

But once did it with a small mill as an Apprentice.

Bad habits die hard!

Howard

I used to own a large IXL-badged lathe with power long and cross-feeds. Those were engaged, not just selected, by a lever with pull-out locking-pin, on a quadrant on the saddle. The action was quite stiff, and it was 'orribly easy to over-shoot mid-gear.... I kept a bolt lying loosely in the "spare" pin-hole to prevent the potential ooh-nasty.

(I sometimes wonder what happened to that machine, which was complete with all accessories, change-wheels etc. I was persuaded to donate it to the Lynton & Barnstable Railway's workshop, but I don't know if they still have it. If not I hope it has found a new, loving home.)

My hard of thinking is usually to measure once, measure twice, even measure thrice and cut once.... to the wrong length.

Funnily enough my technique is to measure twice, forget the first reading, measure twice again.....

I’ve tried drilling with a cordless set on reverse … thinking “this drill’s really blunt!”

Me too.

Strange thing was the sense of total confusion that descended and stopped me spotting a very obvious mistake.

The previous step in a sequence had been threading in reverse, surely a strong clue, but my mind ignored thgat and jumped straight into considering awful faults, like a failed VFD, disintegrated bearing, cracked headstock , de-toothed gears, etc etc. Didn't last long, but I lost situational awareness! Good job I wasn't flying a Jumbo Jet!

Dave

Yep me too. Chipped 2 faces of the 3 cornered one before i noticed it was in reverse..

Steve.

In the same vein,wasted two afternoons, at various times, checking the wiring to work out why the lathe would not and was devoid of electrical power.

THEN, noticed that I had leaned on and latched in the Emergency Stop button.!

Experience allows you to recognise the mistake the next time that you make it

Howard

Years ago, I built the little GHT 3" rotary table. I made my own T-slot cutter, silver steel, complete with thread for Clarkson collet chuck. It was only as I was about to switch on that I realised that I had cut the teeth left-handed...

Had to rewire the Dore-Westbury to run backwards and hold the cutter in a Myford collet. Thank goodness for D-W spindle nose being Myford copy. It cut beautifully in mild steel - eventually.

Haven't made that mistake again. Made plenty of others, though! It's called experience...

Same here i looked at the plans double checked the measurement on plan then marked the piece did this three times then cut only to find I took the measurement from the plan view and not the side view

The Smart & Brown model A at the museum has a guard over the reverse switch to reduce the risk of error, I have only used it for threading 2.5mm trapezoidal nuts for the drill mill, and with left hand boring bars, having locked the chuck on the threaded spindle first. I wasn't sure about reversing an old machine like this and asked for advice on the forum before trying it. Reversing at low speeds without stopping first turned out to be a doddle, with no noises or vibrations as I had feared.

 The 2.5mm trapezoidal thread was easy to obtain as the idler gear was 125/127, the exact ratio to use with one of the imperial thread pitches. The first test was a failure, the nut would not screw on very far despite being made somewhat oversize. My mistake was as simple as changing from 125-127 to 127-125

Edited By old mart on 07/07/2022 21:01:34

My milling instructor said that in the loco erecting shop, his favourite was a 6 foot steel rule. Said that it prevented him being accurate to better than a 64th, but an inch out!

My turning instructor was so experienced that he could use his steel rule to get with a couple ,of thou of finished size. Forty years experience!few

IF only I could be that good

Howard

I made another daft mistake in the workshop yesterday, and this time I decided to walk out the door for the evening...

I'm not a fast worker, so I was on the second evening of making some blowdown valves. Just finished one, wanted to just knock a little sharp edge off of one part using the linisher. My clumsy handling made the linisher spit the bronze part across the workshop; I didn't see where it landed. It still hasn't turned up.

Sometimes going inside for the evening is the best thing for the sanity...