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ForumindexVerkstadsforumVerkstadenSvarvning/fräsning/borrning/slipning

Örnmaskiner Lathe

12 inlägg • Sida 1 av 1
Diskutera skärande bearbetning (svarvning, fräsning, borrning, slipning) här

Paska (trådstartaren)

#1 » 18:21:56, 04-10-2018
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Hello there,
I got an old big örnmaskiner lathe in the garage, (has no type plate so don't even know the model or year of manufacture) i have a problem with the spindle being not inline with the ways. It turns taper when leveled (about 0,06mm per 100mm) and it can not be removed by twisting the ways by the adjusting feet. Problem is that the gearbox unit is aligned to the ways with the vee and flat on the ways. So any thoughts if the spindle can be aligned and am I totally hopeless with that machine. Sorry not speaking swedish but i thought as the lathe is swedish there might be some people who knows something about it. Thanks.
Paska
Fler än 1 inlägg
 
Blev medlem: 17:59:50, 23-10-2017
Ort: Rantsila
Suomi Finland (finska)
Maskintyp: Traktor
Maskin: Mf 135



jörgen.ottosson

#2 » 19:21:05, 04-10-2018
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Hi and welcome to the site!
If the lathe has bin sitting badly leveled with the bed twisted for some time ( be fore you bought it ) it may be that the twist in the bed takes some time to get out ( with out forcing it ) ......so you may have to adjust it the best you can, and wait a few weeks, than adjust ones more ......and ones more....and so on, until the twist is out.

Is the twist constant over the bed ( it cant be leveled ) ....or is the bed leveled (= not twisted) but it still turns a taper?

Does it turn a taper that is "even" from the shuck on, (= for instans, the diameter is largest near the chuck and drops off the further from it you measure) or is it an uneven taper ( = the diameter of a test bar varies, for instans: from large to small, to large a gain, along the length of the bar?

The headstock is probably aligned correctly from the factory, but the bearings may be worn, specially if it is plain bearings that has seen no oiling ?
Deus ex machina
jörgen.ottosson
Fler än 500 inlägg
 
Blev medlem: 22:57:47, 04-01-2009
Sverige
Maskintyp: Grävmaskin (larvburen)
Maskin: sandvik sl-350
liebherr a500s
scania lbs 140
KL 121B

Paska (trådstartaren)

#3 » 20:14:45, 04-10-2018
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Thanks for your reply, makes sense to me that it can be one of the possibly many reasons for that. I have freshly adjusted the spindle bearings and they have now reasonable preload in them and the spindle runs very true. I think i need a better precision machinist level to see where the problem really is before hesitating too much.
Paska
Fler än 1 inlägg
 
Blev medlem: 17:59:50, 23-10-2017
Ort: Rantsila
Suomi Finland (finska)
Maskintyp: Traktor
Maskin: Mf 135

jörgen.ottosson

#4 » 20:34:38, 04-10-2018
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A machine level is probably a good idea. But I hope yore not aiming to get the late "dead acuate" ( = 0,0001mm taper, or so...)

0,01-0,02mm/300mm is what you can expect from a new (high quality) lathe (parallelism of head stock to the lathe bed, and that is only measured on one side of the testbar, when you turn a shaft and measure the diameter the differences is two times larger, you measure on both sides of the part. .......so if you get your lathe near three or fore times that that, is grate! .....but I would personally settle for less.
Deus ex machina
jörgen.ottosson
Fler än 500 inlägg
 
Blev medlem: 22:57:47, 04-01-2009
Sverige
Maskintyp: Grävmaskin (larvburen)
Maskin: sandvik sl-350
liebherr a500s
scania lbs 140
KL 121B

Paska (trådstartaren)

#5 » 21:49:15, 04-10-2018
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I would be statisfied even if i can't get it so straight, but the current taper is too much and requires immediate actions to not scrap parts. I have done some pressfits with it already, and they do not turn out too well with that much taper in them. My use has actually no need for very long dead straight parts, maybe 100mm is the longest part i need to get fairly within 0,02mm. And i can finish od journals and things like that in my tool and cutter grinder to get them meet the better specs i might need.
Paska
Fler än 1 inlägg
 
Blev medlem: 17:59:50, 23-10-2017
Ort: Rantsila
Suomi Finland (finska)
Maskintyp: Traktor
Maskin: Mf 135

jörgen.ottosson

#6 » 06:14:42, 05-10-2018
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A used lathe often taper a bitt when the apron is closest to the chuck ( as it then enters a relatively unworn part of the bed, or if a gap is fitted, with out seating it correctly, and the apron enters on to it ) although the lathe is leveled.

This can often be observed when boring short parts.......if the taper is clos to the chuck, extending the top slide ( or boring bar) may help (this is not god for the rigidity but it makes the apron stop a bitt further away from the chuck, before it enters the "unworn part" of the bed.

I'm not positive this will work, but it it worth trying.
Deus ex machina
jörgen.ottosson
Fler än 500 inlägg
 
Blev medlem: 22:57:47, 04-01-2009
Sverige
Maskintyp: Grävmaskin (larvburen)
Maskin: sandvik sl-350
liebherr a500s
scania lbs 140
KL 121B

Paska (trådstartaren)

#7 » 07:42:37, 05-10-2018
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Thanks, i will dig more into it in the next few weeks maybe.
Paska
Fler än 1 inlägg
 
Blev medlem: 17:59:50, 23-10-2017
Ort: Rantsila
Suomi Finland (finska)
Maskintyp: Traktor
Maskin: Mf 135

Paska (trådstartaren)

#8 » 12:22:03, 21-10-2018
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So i have now leveled the ways with a precision level, they still have some very little twist on them that is hard to remove. It now turns actually more taper than before leveling, so i think what i next do is to lift the headstock off the ways and clean the mating surfaces well. And by the same i see if some of the previous owners has tried to shim the headstock to remove the taper that was caused by twisted ways.

1 person gillar det här inlägget.
Paska
Fler än 1 inlägg
 
Blev medlem: 17:59:50, 23-10-2017
Ort: Rantsila
Suomi Finland (finska)
Maskintyp: Traktor
Maskin: Mf 135

jörgen.ottosson

#9 » 12:57:36, 21-10-2018
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Paska skrev:.... if some of the previous owners has tried to shim the headstock to remove the taper that was caused by twisted ways.


That might be the case.
Deus ex machina
jörgen.ottosson
Fler än 500 inlägg
 
Blev medlem: 22:57:47, 04-01-2009
Sverige
Maskintyp: Grävmaskin (larvburen)
Maskin: sandvik sl-350
liebherr a500s
scania lbs 140
KL 121B

Paska (trådstartaren)

#10 » 19:27:19, 28-10-2018
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Okay, i lifted the headstock off and cleaned the mating surfaces, it now turns taper slightly to the other way... 0.05 by 300mm. I think that starts to be somewhat reasonable for an old machine like that, i'll try now to make it still a little better by doing some fine adjusting on the leveling. Thanks for the tips Jörgen!

1 person gillar det här inlägget.
Paska
Fler än 1 inlägg
 
Blev medlem: 17:59:50, 23-10-2017
Ort: Rantsila
Suomi Finland (finska)
Maskintyp: Traktor
Maskin: Mf 135

jörgen.ottosson

#11 » 20:16:37, 28-10-2018
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Nice work !

0,05mm taper over 300mm ( I assume You are measuring the diameter ) is half that in realty ( measured on the radius....the actual variation (error) from the theoretical center line of the part) and 0,05 / 2 = 0,025mm is very close to "new lathe tolerances"

Tweaking it might do the trick, butt it will probably shift the error to a new location ( along the bed)
Deus ex machina
jörgen.ottosson
Fler än 500 inlägg
 
Blev medlem: 22:57:47, 04-01-2009
Sverige
Maskintyp: Grävmaskin (larvburen)
Maskin: sandvik sl-350
liebherr a500s
scania lbs 140
KL 121B

Paska (trådstartaren)

#12 » 04:06:04, 31-10-2018
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Yes I measured diameter, I'm going to call it good for now. This amount of taper should cause no problems with my projects.

1 person gillar det här inlägget.
Paska
Fler än 1 inlägg
 
Blev medlem: 17:59:50, 23-10-2017
Ort: Rantsila
Suomi Finland (finska)
Maskintyp: Traktor
Maskin: Mf 135


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