9:1

That's the reduction ratio of the unit I'm building for an X axis power
feed for my mill . Input will be an HF 18v motor from a drill powered by an
18volt wall wart thru a PWM controller for speed control . Gearset is
loosely copied from a Logan reduction gearset in my QCGB . 16t input gear
drives a 48t which is pinned to another 16t which drives another 48 . Input
and output are concentric , I'll be copying the drive dogs on the leadscrews
for both in and output . So far I have the gears made and sideplates
machined . I still need to make an axle and bushings for the 16/48 pinned
pair , bushings all 'round , and the input and output shafts .
I'm using 20DP gears cut from a JD tractor (from my 317 , badly worn)
axle for the small ones and from a piece of 4140-type stock that used to be
shipping bracing for a 5 x 12 foot CNC router table . Side plates are 1/2"
aluminum stock , holes drilled then final machined with a shop-made boring
head . In a little while I'll be out in the shop getting started on the
in-out shafts and bushings .
This will give me enough low speed torque for smooth slow feeds , with the
top speed at 100RPM's at the output - I tried this motor directly coupled ,
but low speeds were jerky . Not all that fast , but a lot less work that
cranking tha wheel by hand . The big benefit here will be much more
uniformity in feed speeds and therefor much better surface finishes . Final
configuration for controls hasn't been decided yet , but I do have
everything but a DPDT reversing switch in hand . Coming next will be a belt
driven feed for the Z axis , for those times when I use the boring head and
need a very smooth finish .
--
Snag
Reply to
Terry Coombs
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"Terry Coombs" fired this volley in news:ml275c$klg$ snipped-for-privacy@dont-email.me:
You can waste SO much time not using good servo drives, and just doing it 'right' the first time!
You'll regret this strategy... but it'll come late, when you realize that the motor won't last long enough to serve you well. And then you'll be 'stuck' with a non-standard PWM system that both doesn't deliver AND will make you replace it.
Lloyd
Reply to
Lloyd E. Sponenburgh
Ah , but I will have the pleasure of having done it myself . Lloyd , this ain't a production shop , and probably 90% of the time I'm going to be cranking those handles manually . This is for those times that I need some measure of uniformity . And the Z will probably be done using one of the stepper motors I have . They're not powerful enough for the X or Y , but should work OK for the Z - especially with 2:1 or 3:1 pulley ratios .
Reply to
Terry Coombs
"Terry Coombs" fired this volley in news:ml2gce$oi0$1 @dont-email.me:
Non-sequitor. I've built CNC systems from 'proper components' myself, and you could, too. And it ultimately costs less than the troubles you'll have with cobbled-up components.
"Do-it-yourself" has never intended to mean, "doing it the cheapest way possible, without regard to results".
Lloyd
Reply to
Lloyd E. Sponenburgh
I kinda agree with Lloyd on this one. Better to have it and not need it then to need it and not have it.

Reply to
Bob La Londe
o needing it and not having it. And building power feeds is every bit as m uch fun as building say a steam engine.
Dan
Reply to
dcaster
Who said anything about CNC ? I'm just trying to get a decent finish with a face mill . If CNC is in my future , it won't be with cobbled components . Ballscrews , servos , all kinds of things involved in building an integrated system - and that ain't happenin' with what I have to work with AT THIS TIME . What I'm building will fulfill a need that *I* have , whether or not if fills a need YOU have is irrelevant.
Reply to
Terry Coombs
Gunner Asch on Sun, 07 Jun 2015 19:08:01 -0700 typed in rec.crafts.metalworking the following:
DIY often means "We could have bought it for less ... but it was the process which was why we did it."
Friend observed that, really, what he has invested in the time, travel and wandering around - he could have gotten a job flipping burgers and bought the stuff (he was getting at garage sales) new, and still come out ahead. But that wasn't why he was out shopping the yard sales in the first place. -- pyotr filipivich "With Age comes Wisdom. Although more often, Age travels alone."
Reply to
pyotr filipivich
I heartily agree! Not only the process, but the continuing satisfaction when using the product of our own doing. However ... when the results of doing it ourselves are not what we expected, there will be disappointment; directly proportional to the time, effort and care that we put into the project. Snag is putting a lot of care into his project and there is the potential for a lot of disappointment.
I see the drill motor & PWM drive as the weak link, especially regarding constancy of feed. For a powered feed on my lathe, I used a servo amp with tach feedback and it's amazingly constant:
formatting link
Buying the servo amp might be less satisfying than building your own PWM drive, but I still get a REAL NICE feeling every time I use my power feed.
Bob
Reply to
Bob Engelhardt
Bob Engelhardt fired this volley in news: snipped-for-privacy@news6.newsguy.com:
That was my whole point. It's not just "not quite the best solution", it's a cobbled-up thing bound to disappoint fairly soon after implementation.
Lloyd
Reply to
Lloyd E. Sponenburgh
The way this is designed , I can change the power source if the need arises - and I did consider using one of the stepper motors I have , but they're not powerful enough for this task even with the torque multiplication from the reduction gearing . Several pieces were cast in my aluminum foundry ... if I could have found a "real" power feed unit for less than a quarter of the cost of the mill itself , I would have bought one . I toyed with using a wiper motor , but the ones I have available all have stripped worm drives . -- Snag And hey , if it doesn't work out as well as I want , I still have a really nice reduction gear set .
Reply to
Terry Coombs
Bob Engelhardt on Mon, 08 Jun 2015 09:08:53 -0400 typed >> DIY often means "We could have bought it for less ... but it was
"I'm not sure what I wanted to do, but this wasn't it." said after renting a tractor for some back yard landscaping. -- pyotr filipivich "With Age comes Wisdom. Although more often, Age travels alone."
Reply to
pyotr filipivich
I looked through the scrap yard today and found two motors with gear reductions that might work well for that. They were from battery powered wheel chairs. They work, but are noisy. They have a lever to disconnect the drive.
So maybe you could check with medical supply / repair places and find something in their scrap that would work well.
Dan
Reply to
dcaster
snipped-for-privacy@krl.org prodded the keyboard with:
What on earth is wrong with a normal wiper motor ? I have now built two and they work great ! Tumbler reverse, centre off and variable speed.
Reply to
Baron
I have a couple of wiper motors , but the worm gear is messed up in both .
Reply to
Terry Coombs
The worm or the worm gear? In either case maybe you would like to try making your own worm and worm gear. It is actually pretty easy, I know because I have done it. What you need is a high spiral tap that is the diameter you want for the worm. Then you can use a piece of a bolt for the worm or you can single point one. Then for the worm gear, also known as a worm wheel, you decide how many teeth you want and using this number and the pitch of the worm and pi you can determine the OD of the worm gear. Make a disc the proper OD and thickness with a hole through it. Then make a mount for the lathe to hold the gear blank horizontal and use the hole for an axle. Put the tap in a collet or the chuck and make sure it runs true. Adjust the center height of the disc so that it is on the spindle center. With the tap spinning present the disc to the tap and start feeding in. The high spiral type of flute on the tap will make sure that the tap is always engaged with the work and so will pull the worm gear around as it cuts. So the tap acts as a hob. When I made my worm and worm gear sets I first used some all-thread to see if it would work. It did so I made worms from O-1 and heat treated them. I made the worm gears out of bronze.. They worked quite well. Eric
Reply to
etpm
All that instead of another junkyard motor?
Reply to
Jim Wilkins
Terry Coombs prodded the keyboard with:
Yes they can get damaged when someone drags the wiper blade across the windscreen. Just dump them or use them for something else. My local scrap yard often gets vehicles in for disposal. Often the scrap man will let you go in and take off any parts that you might want. Quite rare at the moment but electric window winders are good too !
Reply to
Baron

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