Author Topic: Hello from Swazi  (Read 4223 times)

Offline Steenkamp

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Hello from Swazi
« on: May 21, 2015, 06:12:11 AM »
Hi All, Im Rhynardt from Swaziland. Been a lurker on Mad Modder for a bit now just sucking in info. I have a small machine shop with a Myford ML7 lathe, a unknown beleived to be Russian round bed lathe and a TomSenior M1 mill. Have dabbled around with small steam and sterling engines, turbines and tooling. Current work in progress builds are a tool and cutter grinder made from a old Black & Decker valve grinder , another gravograph single lip cuttergrinder i have modded to gring the ends of milling cutters and giving the round bed russian a powerfeed.

My Tom Senior has a "Knuckle Head" vertical attachment and i use this for most milling tasks. My problem with it though is that the head severely limits headspace and the worst problem is my two helical drivegears for the spindle in the head are almost non existant. I think the machine had a very productive previous live as they are worn very sharp! Getting new gears made will cost more than i would pay for a chinese mill! I really dont want to part with the Senior as its a superb, very rigid and still accurate machine.
What i have been contemplating is to build a new "M head" type spindle that bolts to the top of the machine and remove the knuckle head completely. What bearings could i cost effectively use. I did some enquiries regarding "super precision" angular contact bearings and the pricing on those are prohibitive. Any other suggestions?

Offline PekkaNF

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Re: Hello from Swazi
« Reply #1 on: May 21, 2015, 06:58:01 AM »
Wellcome! Here seems to be some people from RSA.

RE: Shopbuild spindle and bearings...I have been tinkering with some stuff like that and I have arrived to this:

1) Book Spindles by Harprit Sandhu
http://bbs.homeshopmachinist.net/threads/1360-Book-Review-Spindles-by-Harprit-Sandhu
This might a little basic, but still best I have found for amateur. Some "metric" dimensions and bearing sizes are funny, best to check.

2) Super accuracy bearings are more of a nuisance than benefit on homebuild....If you read the bearing book, your head will spin when you see requirements even for a normal bearing housing dimensional accuracy. More stiffer and accurate bearings you require harder it gets and let's not forget the preload, lubrication and heat buildup. Yherefore I recommend using C3 for ball bearings and standard for angular contact bearings and taper roller bearings.

http://www.skf.com/ph/products/bearings-units-housings/roller-bearings/principles/bearing-data-general/bearing-internal-clearance/index.html

3) Main Loading direction and rpm will get you very close to correct bearing:
* Slow rpm and lots of load = taper roller bearing. Cheap (wheel bearings and such), but you need external shield/seals.
* High rpm and you don't plan hitting the arbor to free the MT-taper = angular contact bearings. These are pretty cheap and often come with a seal.

Then only thing left is to use them in opposing pairs or use another arrangement  for preload and temperature compensation. That's pretty much all I know there are people on this board who know these things or have build something similar. Why not make a thread on this one, lot's of pictures of the "victim" and some doodle?


pekka

Offline Steenkamp

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Re: Hello from Swazi
« Reply #2 on: May 21, 2015, 09:00:37 AM »
Hi Pekka, thanks for the advise. I was thinking around the same thing regarding standard angular contact bearings, just didnt wanna say it out load incase i offend the purists. Will definately post some pics of my machines. Watch this space a bit later today.

Offline vtsteam

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Re: Hello from Swazi
« Reply #3 on: May 21, 2015, 11:02:17 AM »
Hi Rhynardt, welcome!!! :beer: Looking forward to your progress, photos, and contributions!

Don't worry about "offending purists" here. Not enough purists to offend on MadModders! Opinions, yes, but usually when asked for. Generally an extremely helpful, interested, and supportive group.

I'm not familiar with your mill attachement, so if it has a quill, this wouldn't apply, but if not, it's possible to buy a spindle and tapered roller bearings meant for a mini-lathe quite reasonably, and it's ground, keyed, pre-bored for and MT taper.

Personally, though (here comes the opinion) I'd be very interested, if it were mine, in cutting new helical gears for the spindle. Where there's a will there's a way, and I bet with some research, it coud be done in the home shop.

There was a great gear cutter project by DT Jacobs in old ME's that certainly could have done it, and I think a simpler shop built fixture for a one-off job might be built for the lathe (or mill) with some thought about the requirements.

Anyway, once again, welcome aborad!  :beer:
I love it when a Plan B comes together!
Steve
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Offline krv3000

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Re: Hello from Swazi
« Reply #4 on: May 21, 2015, 05:21:32 PM »
hi and welcome

Offline modeldozer

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Re: Hello from Swazi
« Reply #5 on: May 22, 2015, 08:45:55 AM »
Hi and welcome from an ex South African.

Abraham

Offline Steenkamp

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Re: Hello from Swazi
« Reply #6 on: May 22, 2015, 01:03:56 PM »
Thanks for the welcome vtsteam, krv and Abraham. The mill has a 90 degree knuckle for vertical milling, no quill, just a knee for Vertical movement. The helical gears are still a bit above my experience level. Another reason to make another spindle is to increase headspace, fairly limiting factor on my mill. Another limiting factor is spindle speed, max speed on the current spindle is around 1000rpm, a bit slow for my small 3 mm mills i use for engines. Will try and get to a larger town in South Africa tomorrow to look for some bearings

Offline petertheterrible

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Re: Hello from Swazi
« Reply #7 on: May 24, 2015, 12:42:23 PM »
Welcome.  Off note there is a guy on the SA Gumtree at the moment selling castings of a Steam-engine, if anyone is interested.  Rhynard, big fan of the Tom Seniors. :drool:  With the constraints we often face in engineering in general, I often find myself using taper rollers of the type used as wheel-bearings for trailers and Land-Rover differentials.  If your making from scratch you will have leeway on the types of bearings to be fitted.  Whatever type of bearing you use, I would advice to overrate to the point of ridiculousness, only my personal preference in doing stuff.  Make it temporary, when you master helical gears you can always fix the old head. 

A cheap fix would be to go to the junkyard and get a light truck front hub, cut off the flange where the wheel studs are and with two brackets and a precisely made spindle you can actually end up with a decent head.  Hubs come in different sizes and so to do milling machines, upper seal supplied only need a lower one and in some instances on really old hubs you can even use the axle as a spindle.  Not to say that this will be relatively compact. 
Terrible by name, worse by profession.

Offline petertheterrible

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Re: Hello from Swazi
« Reply #8 on: May 24, 2015, 12:51:48 PM »
Forgot to add that this would be my method of making a belt driven head with independent motor and mounting brackets.  Disclaimer: Use only relevant advice and ignore gibberish.

Off to make a furnace blower from a Hamster Harvester, good luck :dremel:.
Terrible by name, worse by profession.

Offline Fergus OMore

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Re: Hello from Swazi
« Reply #9 on: May 24, 2015, 01:24:07 PM »
Hi, greetings from the North East of England. I certainly recall a Round bed Russian Lathe which would be some 40odd years ago used by a 'night school' student at Gateshead. I had a RB Drummond and
Mk1 Unimat then

I found my old Drummond RB useful then. It went to a friend who used it for woodturning.

Enjoy!

Norman


Offline Meldonmech

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Re: Hello from Swazi
« Reply #10 on: May 24, 2015, 01:41:40 PM »

 Hi
                Welcome to MadModder, you have already a well equiped workshop. Your milling head looks like an interesting project, which we look forward to following on the forum.

                                                              Cheers David

Offline Steenkamp

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Hello from Swazi
« Reply #11 on: May 25, 2015, 04:49:04 AM »
Hi guys. Bearings will be arriving today. Have gone for angular contact bearings  for spindle bottom and a deep groove ball bearing for the top, will see how that works. Will be starting a new build thread on the head. Got the base of my rotary table made this weekend, so while i was waiting for bearings to arrive i could atleast do something

Offline Steenkamp

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Re: Hello from Swazi
« Reply #12 on: May 25, 2015, 05:13:07 AM »
Hi Guys, i promised some pics of my machines , so here goes. The last photo is of my Gravograph single lip grinder i modified to grind end mill ends. Have another Black & Decker valve grinder that im still working on. So many projects, such short weekends!