Martin w
Ultra Member
I have a piece of bed way wiper felt left over from my K&T mill, I had. I’ll throw it in when I come to the meetup in Aylmer. How thick are your felts?
Martin
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Mystery lathe, for real
- Thread starter MashingMetal
- Start date
Martin
Is this one of those - you need a lathe to fix a lathe deals? I guess that's why we all need two lathes!
Seriously though, I think the hardest part of this job is gunna be buying or grinding the threading tool.
skippyelwell
Ultra Member
Probably 1/8th" but what was left of them was hard, crumbly and had to be chipped out of the shield. I only need about 4 square inches.
Thanks
I could have saved you the effort, but good to know they are still pursuing the same 'business' model. There are companies in the UK like this too -- anything aligned with 600-Group, for example.
The printed plastic wipers that are widely available on eBay.co.uk are cheap and work well in my experience. I crashed one of them into my bed stop, but otherwise they are going strong after 2 years. The originals were some kind of phenolic so the 3D printed plastic is a closer match than felt, but I can't see why felt or leather wouldn't work as well or better as long as you still have the 4 cover plates intact. I don't .
There is a fellow on UK eBay that runs a small production of top- and cross- lead screw nuts for our lathes. He always has something listed, but maybe not showing Chipmaster at the moment. Find him and use the contact seller utility. Last I checked he provides a cross slide imperial chipmaster nut for about 50 pounds sterling. These are 2-start threads, std acme I think, so a tap is not something you are likely to find off the shelf at McMaster -- I don't recognize the other link that was suggested. Before going this route, check that the backlash is uniform across the screw or you just replace one problem with another. No offence if you already know that and have done the check. If yes, it may help your backlash significantly to get a new nut. There was an anti-backlash option on the cross for chipmaster, but mine doesn't have it. Last time I had it apart I put the nut in a 10 T press and 'squished' it a bit. Took out all the troublesome slop, and likely a temporary fix, but of course you will never get it all out. There is a 'new old stock' cross slide screw currently on eBay in metric. If you run with a DRO, that would not be a significant compromise.
skippyelwell
Ultra Member
I was window shopping on ebay.uk as you suggested and I found that ad for the Bantam cross slide screw nut, 37 pounds and 13 pound shipping, that is more like it.
I think the 3D printed wipers were like 9 pounds, it's a good source, thanks for mentioning it.
I have a 20T press so the squish is a great idea but probably the last one I try after I make a new one.
I thought I would try modifying the worn out nut by making it adjustable just to see what the results would be, the black marker line would be the cut up to about the middle of the hole and 2 screws to pinch the threads together.
I started cleaning up the 3ph 575v motor today, I always get a kick out seeing the conditions these machines are run in.
The black stringy fibers that are wrapped around the cooling fan looked like old cassette tape.
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Nice work!
Is it my imagination or are the nut threads very heavily worn?
There are lots of ways to do this.
Depending on how much room you have on the rounded side of the nut, you can mill a narrow flat and add a bending leaf so the slot can extend beyond half the screw bore.
You can make another nut with a flat for the leaf above or a deeper cross-section to accommodate an extended slot.
You can cut it right through and add alignment slider pins.
The screws can pinch the nut by tightening or widen it by pushing.
Lots of other ways too.
Is it my imagination or are the nut threads very heavily worn?
There are lots of ways to do this.
Depending on how much room you have on the rounded side of the nut, you can mill a narrow flat and add a bending leaf so the slot can extend beyond half the screw bore.
You can make another nut with a flat for the leaf above or a deeper cross-section to accommodate an extended slot.
You can cut it right through and add alignment slider pins.
The screws can pinch the nut by tightening or widen it by pushing.
Lots of other ways too.
skippyelwell
Ultra Member
So once you add the bending leaf into the slot, you peen the bronze over to keep the leaf in place?
I can't see the nut threads, but the eyeball metric on the screw suggests it is worth checking (I mean measuring, exactly) the backlash mid screw vs front and back. The best you can do is take it mostly out front and back, so if the difference is a few thou, that is going to stay, new nut or modified nut, or whatever. Luckily someone (probably unintentionally) kept my cross screw well oiled and my original backlash was uniform at about 10 thou. The nut squish thing (one small step at a time and check) brought it into what was probably the original designed backlash, more like 2-3 thou and the same across the travel. The reason I say it is a temporary fix is I doubt the close up on the threads was uniform, so I'm running on a reduced nut -- wear will eventually catch up with me and not 50 years later like the original
skippyelwell
Ultra Member
Oh the threads in the screw nut are razor sharp, quite sloppy.
Birkhoff, I stumbled onto these guys, parts galore, https://www.colchesterspares.com/machine-gallery
Birkhoff, I stumbled onto these guys, parts galore, https://www.colchesterspares.com/machine-gallery
Yep, I've seen, but never conversed with them. A random check on prices for parts I know shows fair pricing. Travelling steady for chippie, for example, at 100 pounds -- I bought mine for 50 but lots of searching eBay. I consider that fair for a one-stop-shopping experience and sellers who know how to pack stuff. I'd be curious what their shipping quotes are. The fellow I mentioned a few posts ago uses international Royal Mail up to about 20kg and it is very reasonable and fast. There is a hard weight cutoff for the service and other options get really expensive. One thing you will bump into if you start buying much on eBay from the UK based sellers is an odd reluctance to ship off the islands. It can be quite frustrating. Might be a British thing -- we can ship to them from the colonies, but the other way? -- pardon, why?
I've heard that there is some kind of silly regulation in the UK that makes exporting a challenge. Stuff gets shipped and then inexplicably returned by UK carriers cuz some detail was missing. A few rounds of that and sellers get gunshy. It's probably comparable to the ATF in the USA. But I could be blowing magic smoke in the wind out my disposal port. Maybe someone more knowledgeable than I am can chime in if that rings a bell.
terry_g
Ultra Member
I had a SouthBend 10K lathe that was metric. I needed both the compound feed and the cross feed nuts for it. Imperial ones were available at a price but metric ones were not available. I made a tap to cut the compound nut if I remember correctly it was 10mm x 2.5mm Acme. The tap was made from w1 drill rod hardened and tempered.
It took so much force to cut the threads that the tap twisted but it did the job the new nut was a tight fit on the threaded shaft.
I cut the cross feed nut threads with the lathe, they were 12mm x 2.5mm left hand threads. I removed the cross feed screw and tightened the cross slide gibs so the slide would not move and once the threads were close to finished I would try to thread the cross shaft into the nut. If it didn't fit I would take another .001" cut and try again. The cutter I made for the job was ground from a blade from a small expandable reamer.
It was the first time I ever cut Acme threads. I made a few practice cuts on some scrap aluminium.
It took so much force to cut the threads that the tap twisted but it did the job the new nut was a tight fit on the threaded shaft.
I cut the cross feed nut threads with the lathe, they were 12mm x 2.5mm left hand threads. I removed the cross feed screw and tightened the cross slide gibs so the slide would not move and once the threads were close to finished I would try to thread the cross shaft into the nut. If it didn't fit I would take another .001" cut and try again. The cutter I made for the job was ground from a blade from a small expandable reamer.
It was the first time I ever cut Acme threads. I made a few practice cuts on some scrap aluminium.
skippyelwell
Ultra Member
I'm pretty sure the lathe is metric threaded but I'm getting numbers that don't make sense to me.
I haven't much experience with trapezoidal metric threads but the metric measurement just don't look precise enough.
I used my most accurate digital calipers for the measurements, what do you guys think?
I haven't much experience with trapezoidal metric threads but the metric measurement just don't look precise enough.
I used my most accurate digital calipers for the measurements, what do you guys think?
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I've stared at this for 15 minutes trying to figure out what you are trying to tell us Skippy. I can't help if I don't understand the question. Can you be a bit more pedantic for my feeble mind?
skippyelwell
Ultra Member
Well it's clear in my mind 
Sorry about that, the question is, is this a metric machine or imperial?
The threading chart looks to be in inches, the index rings measure gradations of 100 and 200 which makes me think it is metric.
If it is metric, why aren't the measurements for the for the lead, compound and top slide screws coming out to rounder numbers.
Is "nominal" so loosey goosey that 28.6, 11.7, 6.15mm is considered a standardized measurement for thread cutting?
Sorry about that, the question is, is this a metric machine or imperial?
The threading chart looks to be in inches, the index rings measure gradations of 100 and 200 which makes me think it is metric.
If it is metric, why aren't the measurements for the for the lead, compound and top slide screws coming out to rounder numbers.
Is "nominal" so loosey goosey that 28.6, 11.7, 6.15mm is considered a standardized measurement for thread cutting?
quitereal
Andy
Imperial, but you can still cut metric threads with some different change gears.
I think you have the eagle. The condor would have a real metric leadscrew and metric thread tag.
Eagle:
Condor:
Your measurements there say to me 1.25x4tpi leadscrew
I think you have the eagle. The condor would have a real metric leadscrew and metric thread tag.
Eagle:
Condor:
Your measurements there say to me 1.25x4tpi leadscrew
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Well it's clear in my mind
Sorry about that, the question is, is this a metric machine or imperial?
Don't apologize. No need. I'm the hairy guy eating too many grubs.
I'd bet big bucks that @quitereal has it nailed down for you. But let me add a wee bit to address your dial observation.
Most dials are in thousandths of an inch not feet or yards. Thousandths and hundreds are a decimal (base 10) system. So even though it's an imperial lathe, the dials are still decimal. The 200 dial is 200 thousandths in one turn, and the 100 dial is 100 thousandths in 1 turn. The 10 is ten thou, 20 is 20 thou, etc.
One messy little detail is the duplicity found on cross-slides. Some are marked with 2 thou per graduation and some are marked with one. The difference is usually (but not always) the radius vs the diameter change. The ones marked with 2 usually indicate the change in diameter and the ones marked with a 1 usually indicate the cutting depth or change in radius. Its really all about remembering that we usually measure diameter but cut on only one side so the cut depth gets doubled for the diameter change. It's a mess in my opinion. I'd rather the dial indicated the true movement of the cross-slide and let me do my own doubling for the diameter. (Insert big sigh here).