Lathe fire? Story!


Ray

I suppose lathe fire does sound extreme. It's happened to me only twice now but that's enough to remember. Not actually a fury of fire & no real damage to the lathe other than minor discoloring to the paint. Ti chips are flamable, thinner the swarf, the easier it combusts just as steel wool burns. But Ti burns very white & bright, too bright to look at!

I forget exactly how it happened the first time & I don't plan on trying to find out how to duplicate it. But I remember turning some Ti at probably too high of SFM, saw some very minor sparks but did not think anything of it. Well one of those sparks fell onto the swarf below & a pile ignited. Definitely got my attention real fast!

Second time when I was making the Ti ferro rod holders below. I've made a number of them before without an issue but one time I was facing the ferro rod which sparks very easy if the SFM is too high. Again the sparks fell on a bundle of Ti swarf on the chip pan & boom, bright white light! Ferro sparks like hell so now I flood it with lube when cutting to prevent ignition.

I wish I had a pull out chip pan, I hate when there is long stringy swarf that gets caught & creates a bird nest & is why I take the time to get rid of it when needed. But with the Ti, it's the fine stuff that scares me of igniting, not because of bird nesting.

Hasn't happened to me in a while as I learned what not to do but I always have those memories. Pros may know what they're doing to avoid stuff like this but I learn the hard way. :))


EDIT: This past weekend I had some more Ti chips ignite. If the spindle speeds are on the slow side & I feed to fast/hard I can get a familiar distrinctive sound followed by sparks flying. This time I was boring 4" in depth had had sparks fly out the bore. It was a sight to see but nothing that alarmed me. First time I had sparks shooting out of a bore thow.
 
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These are the spindle speeds I measured using a Monarch Pocket-Tach 100, last NIST calibration in 4-2000 but it should be ok. YMMV.

I'll probably never use the high range but if I do I take the readings & post here.

PM1236_spindle_low.jpg



My thread & feed chart is different from all the other PM1236s I've seen so far. Even though the values are different on my chart I can't imagine the gears ratios to really be different so YMMV. This may not be useful & possibly the chart values can be verified by doing some math but math is not one of my good areas. The lowest measurement below would be my slowest feed rate that's not documented on my chart. My brother estimated 0.001 IPR for my slowest reading but he said there was not enough info based on my chart to get a more accurate estimation.

These readings were taken on the power feed rod at 500 RPM spindle speed & the geabox set to M1.

PM1236_gearbox.jpg


PM1236_spindle_low.jpg


PM1236_gearbox.jpg
 

This was lost in the crash so I'm just reposting....


Thanks to a member of another forum & Gary for the reminder, I got me a 1μm scale for my cross slide too.

Easson doesn't make the size I need so I got a Sino from the guy I get my DRO stuff from in China. Better for me anyway so I won't need any additional work mounting it, simply unbolted the old scale & bolted the new one onto the mounting plate.

Not much to see since the scale doesn't look any different than my original but I'll post some pics anyway.


1μm on top.
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Pic of the X scale mount that I missed in my DRO installation post.
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Scale mounted.
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With the 5μm scales I can occasionally hit .0001" but now with the 1μm I can hit that all the time now.
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With .0001" resolution I'm not crazy to think I can actually try to achieve that level of tolerance, especially with this lathe, but it will help make things just ever so slightly easier. :)
 
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Since you've already done all the hard work, would you like to share the sizes of the slides you used and a source? I know I'll be doing this eventually. :))
 
Since you've already done all the hard work, would you like to share the sizes of the slides you used and a source? I know I'll be doing this eventually. :))

I used 220mm KA500 & 920mm KA300 scales. My source is xiao1207 on ebay. JJ doesn't have a website up yet so you'd have to communicate with him through ebay but he has excellent communication & ships fast.
 
I used 220mm KA500 & 920mm KA300 scales. My source is xiao1207 on ebay. JJ doesn't have a website up yet so you'd have to communicate with him through ebay but he has excellent communication & ships fast.
Thanks, I already have him saved as an ebay vendor, so that works out.
 
That is some good lookin Iron!!!!! Too clean, but the scunge will come in time. I also like the cool air gun too. Have fun and enjoy you new machine...

Bob
 
I have a request for a 30" long Ti javalin/spear that I've been working on. To complete it I'll need an outboard spider so here's my take on making one.


Started out with some 2"Ø CRS.
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Used the 4-jaw to face & center drill both ends.
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Turning between centers.
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Crept up on targeted DOC.
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Test fit, still not enough depth & also needed to tweak the major Ø.
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So back on the centers a few more times until I was happy with the fit. Now it screws in all the way & I'm happy with the fit.
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Drilled up to my largest bit on hand, 1".
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A Fowler electronic edge finder showed up today as I've been curious about them. At $30, cheap enough to give it a try. Have to be real careful with this solid type as the tip does not "break away". It works by contacting the metal & continuity through the mill. I may try the more expensive break away ball type tip later but they have their limitations & advantages because of the ball. Just testing it here, I still just used the good ol conventional edge finders.
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Drilled, tapped, & chamfered four holes.
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Back to the bandsaw to cut off the excess
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Final boring to allow 1.25" stock to fit through comfortably. My spindle bore is just over 1.53"
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The finished spider.
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Now I can continue on with the Ti javalin....
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Thanks for looking!
 

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Good morning - Hey great stuff, this is one of the many things that I need to make (by chance can you post the plans) between you a GaryK you both are keeping me pretty busy.

Thanks,
Sonny
 
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