New powerfeed for lathe - DC variable speed

[J Tiers]

oh.. so now you redefine your statement to mills that are not typical HSM? This entire conversion started about dc drive non-synchronous power feeds, not gear feeds!

BP are not Rong Fu, and probably the most populous "real" mill after clones are counted. Many in HSM hands. Servo Power feeds and its clones are 1-10. Rong etc.. likely not much different

Don't start with me, dragging the discussion off on a tangent. Those are what I was referring to to begin with.... And not because YOU have one, but INSTEAD because evidently THOSE MANUFACTURERS thought it was useful to know the feed rate. It's called an example.....

If they thought so, why do YOU insist that it is BETTER NOT TO KNOW the rate? You evidently need to go to some graveyards and tell those folks how stupid they were!

If you like to remain ignorant of the speed, and just judge it by eye and call it good, go right ahead.... I don't care what you do in the privacy of your own shop.

Some of us do things differently, either because we do not use the machines enough to remember everything, or because we like to avoid trial and error, so we go by the tried and true speeds and feeds when we need to get it right..

It ain;t worth wasting the electrons to argue over it..... I brought it up because the OP mentioned not knowing the feeds....so I suggested a way to know them. I'm not telling YOU what to do.

[dalee100]

Does not come up for me, since I do not have power feed on the mills. So I do it by feel and chip type.

Hi,

So, you are straight up guessing too?

[J Tiers]

Hi,

So, you are straight up guessing too?

Guessing didn't work well....

I can judge the approximate rate on mill by counting turns.... not "guessing", more "getting reasonably close". I'd rather have a power feed, but so far have not got to that priority on the list.

Feed on the lathe is trickier, but again, can judge the rate per handwheel turns 1 turn is an inch and a quarter.... REALLY would like to do that differently, but it is what it is.... not down to that point on the list. Might do a slow feed handwheel.

[epicfail48]

What's the fascination with knowing the exact feed rate number?I don't think anybody here is suggesting that you close your eyes and smack the feed lever to whatever, so it's not like anybody is preaching that it doesn't need to be known at all. Seems like the observation is that you can get all the information that you need from how the tool is cutting, rather than having a fancy chart set up saying that you're at EXACTLY .9845ipr.

[J Tiers]

What's the fascination with knowing the exact feed rate number?I don't think anybody here is suggesting that you close your eyes and smack the feed lever to whatever, so it's not like anybody is preaching that it doesn't need to be known at all. Seems like the observation is that you can get all the information that you need from how the tool is cutting, rather than having a fancy chart set up saying that you're at EXACTLY .9845ipr.

Nobody WANTS to know it like that...

It's handy to know the cut per tooth, and that suggests knowing the IPM within maybe 30%..... Motors slow down under load, etc, etc, so you will not get a lot closer than that anyway.

Industrial folks use the IPM to set up a "process" and know that they will get a certain finish quality from that. They probably want to know it within 10%. You seem to think folks want to know within 0.01%.... why would you think that?

Nobody is telling you what to do, why don't you just let it go......?

[BCRider]

Hi,

Go to monsterguts.com, order a 2 speed 12VDC wiper motor, head over to eBay and order a 6A power supply for less than $10, PWM for less than $10, same for a DPDT switch. Build a box and adapter to drive your lead screw. You now have a $300+ power feed for less than $40.

This will also work for a lathe. If not knowing exactly how many inches per minute your mill feed is running is no big, why would it bother anyone to know about exactly what inch/rev a plain lathe feed is doing?

That's a great plan. Thanks for the item list. Sadly such a project is down around #24. But I promise to post it when it happens.

JCByrd24, good reminder about the lever on the apron I'd still like at least the speed dial to be remoted to the apron though. Just easier to dial a cut from that point with a short reach since the cutter is attached to the carriage. But you're right in that it could just be running the drive rod the whole time.

All in all though I think I'd still include the three position FWD-STOP-REV switch at the same box as the dial. I like the idea of that. I would end up using power feed a LOT more often instead of rarely like I (we) do now. Hell, I can't recall the last time I ever used the transverse feed. And the only times I've used the longitudinal feed is where I have to make cuts of over about 4 inches. And sometimes not even that if it's only one pass. The gear noise bothers me that much.

I would also like to include some way to disengage the tail end drive for times when we did want a direct feed. I don't think it would be often but it would be nice to keep the option open.

[RB211]

I think I will take your method and apply it to my Bridgeport for the X axis.

[lakeside53]

If they thought so, why do YOU insist that it is BETTER NOT TO KNOW the rate? You evidently need to go to some graveyards and tell those folks how stupid they were!

Who said that? not me.

The reality is MOST power feeds do not convey the rate at all, and stuff still gets made.

[chipmaker4130]

. . .Some sort of stop/microswitch setup that stops the feed at a shoulder or something was also discussed, and that would be an added capability.

OK, yeah, I was thinking about post #8 which suggested exactly that. I'd do that in a heartbeat.

[lakeside53]

If you do that it's best integrated with some form of motor braking. Easy to do.

I had exactly that on my prior lathe which has a separate electromagnetic brake. Not only did it work well, it saved my ass a few times With care makes for really nice threading stops very close to a shoulder, closer that you can get without significant pucker.