You need to invest in one or a couple Valenite or OSG indexable insert boring bars. Much better, more rigid and you can the insert after indexing it numerous times plus you can spec them with through the bar cooling that puts coolant and lubricant at the cutting point.
Those throw away brazed carbide bars are fine for small jobs, one time and the carbide grade is questionable because they are made...over there.
From the looks of the chatter, bet it was singing.....
But then. we don't know what kind of toolpost you have. The indexable tooling likes an extremely rigid and repeatable toolpost like an Aloris or Dorian wedge lock.
Always things to consider. You'll need an indexable bar to cut the internal threads anyway unless you are an expert grinder at grinding a throwaway bar to the correct
'It's not about me, it's about we'..........
For ID thread on this spider, I used different boring bar with 1/8 HSS insert, which i had to grind for metric V thread. Anytime I can gets my hands on diamond grinder I sharpen my brazed carbides, I might have to buy one for myself in the future...
As far as toolpost I had thread last year when I was building one, its piston Aloris type...
Aloris and Dorian quit manufacturing piston type posts a while ago. I believe you can still get that flavor in an import (Phase 3) maybe. Aloris and Dorian only make wedge lock posts now because a wedge lock is much more repeatable.
Nice job on the toolpost btw. My Aloris set me back quite a bit. Not as much as the B&S magnetic sine plate, but almost.
'It's not about me, it's about we'..........
Thank you, SidecarFlip ;-) I have no complains with toolpost, just that t-nut on this lathe is weak, I had to make another t-nut to fit this t-slot, I could mill larger slot, but I'm afraid that doing so will weaken compound rest. By the way, I did touch up on the chatter from roughing boring bar. Well now I need to get longer setscrews, the ones I have just a bit short...
Thinking to add spider to my lathe, so I'm planning on building one from 4140. The back spindle is threaded, its metric thread 1.5 the OD is 1400. So I'm thinking to bore out hole for ID thread so I can screw it on the spindle and add setscrews to hold it in place. Well if anyone done this before I'm open to any suggestions...
Here is picture of the back spindle with one nut removed to expose threads.
Thank you ;-)
* 8620 steel will do everything you want, and be easier to machine. Otherwise I'd use 4150 pretreat steel.
* The bearing nut just behind the threads is probably part of the spindle line. DO NOT contact that nut or move it! I would simply thread the bore to seat on the end of the spindle, and then use a jam nut between the backside and the Timken bearing nut. Also would not recommend the use of set screws to hold the spider in place. Will cause you some grief later if you use them.
* and do this before even starting the project. Measure those threads very closely (I'd use three wires in this case), and turn a master to fit the I.D. to. Manufacturers often use oddball pitch diameters with their chucking systems, so forget the book data here. This is especially true with Asian built lathes. I learned the hard way more than once on this issue alone! I've seen pitch diameters cut as much as .015" oversize in this area alone. Once you've made the male master, put it up with some masking tape wrapped around the threads. You'll be glad you did!
I can call mechanism to engage lead-screw or lead screw engager something... About the lathe its 10x22 and it missing some features I would like to have. Let see if you ever worked with Hardinge toolroom lathe, when threading once lead screw engaged it stays that way, but it has a break and special lever on crosslide to get in and out of thread, love that feature... Of course Hardinge toolroom lathe no longer made, but there are many replicas still build today and they still cost 20 times more then grizzly
Here's one made by EISEN
And the one from Grizzly
Swing over bed: 9-5/8" Swing over cross slide: 6-1/8" Distance between centers: 22" Spindle bore: 1" Spindle thread: 1-3/4" x 8 TPI Spindle taper: MT #4 Motor: 1 HP, 110V, single-phase Number of speeds: 6 Range of speeds: 150, 300, 560, 720, 1200, 2400 RPM Leadscrew: 3/4"–12 TPI Compound travel: 3-1/2" Cross slide travel: 6-1/2" Carriage travel: 18-1/2" Maximum tool size: 1/2" Tailstock barrel travel: 2-1/2" Tailstock barrel taper: MT #3
5" 3-Jaw chuck with two sets of jaws 6-1/2" 4-Jaw chuck with reversible jaws 8" Faceplate Steady rest with 1/4"–2" capacity Follow rest with 1/4"–2" capacity MT #3 dead center 4-Way tool post Chip tray and backsplash Hardened & ground V-way bed
Oil-bath gearbox Tool box with service tools Number of longitudinal feeds: 9 Range of longitudinal feeds: 0.0023–0.013 IPR Number of inch threads: 33 Range of inch threads: 8–72 TPI Number of metric threads: 26 Range of metric threads: 0.25–3.5mm Overall dimensions: 46" L x 22" W x 16-5/8" H
when did Hardingh quit building that great little lathe? The only lathe I ever saw that would hang with a Monarch EE. They picked that auto back off up from Monarch, and who knows who Monarch stole it from!
Half nuts; I hate them! But we gotta live with them. Leaving the nut engaged all the time will also give you a better thread form anyway, so go with it. By leaving the half nut engaged you will eliminate a lot of the lead error that is compounded by the dial alone. (I always use the same number everytime)