Design fault in SC2 mini-lathe topslide actuation?
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- Опубликовано: 22 дек 2017
- I found a problem with the gear that moves the topslide (compound rest), when its gib is done up pretty tight. The micrometer dial was sticking. I made a modification that solves it. But it seems to me to be a mistake in the design.
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I noticed this problem when I first got my lathe several years ago. My remedy was to lap both bearing surfaces until mirror smooth. This allows free movement between the surfaces and the flat spring tension was sufficient to allow the micrometer to turn properly in both directions. With this particular modification I do have to lube the surfaces with WD 40 and occasionally am required to remove and thoroughly clean the parts. I also replaced that knuckle busting cap head screw on the handle with a button head screw. It was very annoying to have that cap head interfering with smooth movement by hitting against my fingers. The button head works very nicely.
Very nice. As far as the lift on the top slide goes, I’ve noticed that many small Chinese lathes, for some reason, put the gib on the wrong side. It should be away from the leading edge where the pressure is exerted, as the one for the cross slide is. The other problem is that these gibs aren’t properly fitted. A problem with small gibs like these is that the screws push the gib away from the dovetail in the top slide, leaving a slight space. The gib can wobble about in that space around the screw tips. That means that unless the gib is tightened as to prevent movement, there is enough space to allow that small rise you’ve noticed. I don’t know if the gib has dimples for the screw tips, which should be rounded. But if not, it can move. Sometimes the dimples don’t line up with the tips when they are there. This problem doesn’t occur as much when the gib is in the trailing side. The best gibs are tapers and adjusted with one screw at the end, or in bigger machines, with one in each end. With those, the gib is always in complete contact with both sides.
Thank you for sharing that, mine has the same issue. I will have to do the same.
Hello Samuel, my lathe ( Einhell MTB - 3000 , a mix of C2 and C3 Sieg ? ) had a similar problem. My compound screw is of an older ( ? ) type: no friction spring for the dial ( and no space for that, of course ) but - instead - with a screw through the radius of the meter-dial itself ( to fix that dial in position ); and with 2 nuts to be tightened one against the other, to avoid the screw from going inside alone ( when turning clockwise ), with no any compound motion ... So, when i used to turn the knob clockwise, the two nuts were pushing against the dial, which in turn was pushing against the reference wheel ( that one fixed ... ). Crazy system !
I made a change, now one of the nuts is rebuilt to have also a cylindrical part which goes into the dial ( whose hole was made larger ... ) and pushes directly against the reference wheel.
So the meter-dial is now totally free from screw turning ( clock or anti clockwise ... ).
I reduced the backslash to seven ( or eight ? ) divisions ( carefully adjusting the nuts position ), and the handle now turns nice in both directions ...
Alessandro from Italy.
YOU !! SHOULD !! HAVE !! PUT !! YOUR !! LATHE !! STRÀIGHT !! INTO !! A !! METAL !! SHREADDER !!!
My SC3 has the same problem. Thanks to your video, I can get it working as it should. Keep up the good work!
Thanks. I'm afraid most of my videos nowadays are about autonomous sailing boats, rather than the minilathe. May revisit it a bit if something comes up.
IT !! BELONGS !! IN !! THE !! METAL !! SHREADDER !!!
@@davidwillard7334 SO YOU KEEP SAYING BUT SOMETIMES BETTER FOR PEOPLE TO THINK YOU'RE AN IDIOT THAN YOU OPEN YOU'RE MOUTH AND PROVE IT
Very cool, did mine slightly different I turned a 33mm dia 6mm wide bush bored out 12mm through hole then bored 3.2mm depth 14mm dia for the leadscrew flange and this only mean 3mm lost on the travel worked great (also require slightly longer mounting screws)
Great explanation, helped my understanding a lot thank you : )
I used to have a 920 model which was just a bit bigger than this but very similarly built. The best way I’ve found to fix all of the slide and feedscrew issues was building a new saddle which used myford parts on top of it.
Good job, sir. Thanks for sharing.
Genius! I have to examine mine now!
Thanks for sharing. My lathe has the same issue and now I know the reason why!
BECAUSE !! IT'S !! A !! PILE !! OF !! JUNK !!???
I had the exact same issue and solved it by adding adding a washer between the indicator static ring and the top slide, without shortening the original gib. The washer takes up the load in one direction and the spring loaded dial rotates in every position of the top slide. The top slide screw still has lost a small amount of movement but that is insignificant
Vielen Dank für die Lösung. Ich habe auch so eine ähnlich Maschine und werde es nachbauen. VG
Nice solution. I'm gonna do something similar to mine.
Thanks
JUST !! PUT !! YOUR !! LATHE !! INTO !! THE !! METAL !! SHREADDER !!!!
It is a solution to the issue you highlighted and without prejudice can i sugest you just take a bit of flat bar and drill 3 clearance holes and bolt it to the existing two holes on the front. Allowing clearance for the shaft but not enough for the collar obviously. I think it is more elegant without the need to modify the casting or cut the gib.
As far as I can remember I think that would also work, at the expense of slightly moving the shaft away from the slide, and needing longer bolts. But to each his own.
@@samuelfielder 5mm - 6mm flat bar would do the trick. You might just get away with the same bolts.
That's a good variant on the idea. I think i'll implement this on mine.
JUST !! PIT !! YOUR !! LATHE !! INTO !! A !! METAL !!! SHREADDER !!!
There is supposed to be a half moon, semi round, spring beneath the dial that turns. That spring puts enough preload on the dial, making it turn with the shaft.
Thanks, I solved this problem on mine after watching your video.
Look at Steve Jordan channel, he added two more screws to that slide, tightening them makes the whole assembly rock solid, helps when parting off for example.
Thanks. Yes I intend to add those, as mentioned on the other video's comments. But it doesn't address the micrometer screw problem (when you want the slide to move).
I've never noticed that micrometer screw problem on mine to be honest, mine are imperial anyway, I don't like them much, I just keep checking with my digital caliper in mm.
THAT !!! METAL !! SHREADDED !? MYFORD !!! !! GEEZZA !!! TWIT !! BANG !! GOOD !! SHILL !!! MAN !!!
If you look at the shaft where the dial is positioned there is a wide groove. There should be a sort of leaf spring in there to add friction to the dial and it solves the problem.
It's a battle between the friction created by the leaf spring (radially) and the friction that's bearing against the whole disc by turning the handle (axially). Depending on which one is larger the indicator either moves or gets stuck. Since you want to tighten the gibs to avoid vibration this increases the latter friction until it exceeds the spring friction. So you either have a working micrometer dial, or you have a stable top slide - can't have both with that design as-is.
@@totallynotabot151 Thanks for your reply.. As it goes back a year I was confused what I was posting about so watched the video again. You mentioned the spring yourself when explaining the problem so not sure why I posted above. Your video explains the issue and how you fixed and why so apologies for my post saying a spring adding friction would solve. Good point you make here though as the gibs get tighter so the friction to overcome on the dial increases..I over looked that! There is me trying to mentor you but you end up mentoring me!
great solution to fix a design flaw.
THE !? METAL !! SHREADDER !!! IS !! THE !! ONLY !! SOLUTION !!!
I bored the bracket to accept a small ball-bearing, and loctited the bearing into the bracket and onto the shaft. It solved that problem and in addition reduced the backlash there to something imeasurably small - no shimming required. The sealed bearing came in a packet of 5 for a couple of £ from ebay. I did something similar on the cross-slide.
YOU !! SHOULD !! HAVE !! PUT !! YOUR !! LATHE !! STRAIGHT !!! INTO ! A !! METAL !! SHREADDER !!
@@davidwillard7334 Thank you for that considered and constructive comment.
@@pjday6195 NO !! PROBLAMO !!
Hmm, I have had this model for 20 more years didn’t realize this problem until now. I can’t recall Regis problem now but I might have been resolved this freeing the dial in both directions after adding shim rings, try and error a number of times used up all my patients of the day.
METAL !! SHREADDER !! FIXES !! THE !! PROBLEM !! NO !! END !!!
Nice Work.
Excellent solution
My Harbor Freight 7x12 mini lathe top slide has that issue.
Just a suggestion on your loose top slide ... maybe replacing the gib with a better fitting gib would take that slop out and still allow you to move it..?
Possibly, but I don't have a milling machine, so don't have any ready way of making another gib. I've been watching Keith Rucker making a new gib for his (much bigger) Monarch lathe. Interesting stuff, but beyond my capabilities at the moment! I certainly think the design of the topslide gib - with its three grub screws - is poor, compared to the tapered gib on the Monarch. But of course one has to look to the relative price of these lathes.
Well done fixing the dial, the dial on my lathe doesn't rotate when i move the cuttter and its annoying. I think i can fix that now.
I believe those gibs can be ordered as a whole part, they come a little bit over sized which you could get exact by hand scraping and a micro meter.
Making a replacement completly from scratch without a mill would be difficult.
@@samuelfielder That gib is too wide, instead of a square it should be a rectangle with the thinner sides left and right and same thickness top to bottom. For some reason (or none at all) they cut the compound and ways further apart than they should have.
Two or even one brass ring between the indexing disk would have done the same, and you still would have the same amount of movement range
Edit -I made it and it working like a charm. An indent in the indexing wheel creates room for the washer, removing the awkward space.
Have you by any chance got a picture 👍🏻
METAL !! SHREADDER !! WORKS !! WONDERS !! TOO .!!!
I bought one of these which had digital read outs on both the cross slide and top slide. The top slide dro went up the creek and after much discussion with the supplier's they sent me a replacement unit for a micrometer dial and a dial. One of vital pieces was missing and nothing else fitted. I was informed China are for ever changing the design of parts and no spares are available. I had to bodge-up something which more or less worked but is not at all satisfactory in that the slide is loose and the dial does not go round at all.
I would NOT recommend such a lathe to anybody except a highly skilled engineer who could put it right.
I did some drawings of my bodge-up and am still awaiting an acknowledgement from the suppliers.
JUST !! PUT !! YOUR !! LATHE !! STRAIGHT !! INTO !!! THE !!! METAL !! SHREADDER !!!
@@davidwillard7334 I took it there but they wouldn't take it!!!!!!
@@bbcisrubbish Well ! TAKE !! IT !! SOMEWHERE !! ELSE !!
Mine is different and maybe not so good either. Mine has a grub screw on both axis that holds the dial from moving that solves the problem, but also makes it so that in order to set the zero I have to use an allen key to loosen the grub screw. No springs in mine at all, so they have cut corners again.
METAL !! SHREADDER !! IS !! THE !! ONLY !! OPTION !! FOR !! YOUR !! LATHE !!!
nice one, my lathe does have a grub screw on its dial which lock the dial on feed screw , it may be a good to add one on yours
Yes, a grub screw is yet another way of solving this problem, but of course you'd then need to undo it every time you want to zero the dial.
Would it be possible to use a grub screw plus a spring and a ball bearing, that way you may not have to back off the grub screw.
@@adoreslaurel the dial diameter is not that big on mini lathe , however is possiable to do that but I don't see any point to do it
@@ParsMaker Ok, thanks for that.
JUST !! PUT !! YOUR !! LATHE !! INTO !! THE !! METAL !! SHREADDER !! FIXES !! IT !! NO !! END !!!
Cool... but have you tried rocking the topslide forward and backward to see the amount of play ?
based on the backlash I see at the end of the video I am sure there will be plenty of rocking back and forth as the slack is taken up between the two microm dials.
THE !! METAL !! SHREADDER !! SHOULD !! FIX !! THAT !! NO !! END !!!
The slide rocking is nothing to do with leadscrew backlash and all to do with extremely poor build and fit of dovetails and gib. I doubt it would be possible to put any less effort into building these and still end up with at least somewhat working machine.
you could have just made a Lead Screw Nut for it, like the South Bends and Jets/Grizzlys have. at that you would not have to shorten the gib.
I have to ask is this by the colour on the lathe, is it an Axeminster supplied unit ?
Yes it is an Axminster one. I think the Warco one is slightly different.
@@samuelfielder I have been looking at a SIEG C3 chinese import lathe, which on looking and comparing them seem identical, bar the paint colour is this correct.
All these lathes are made by Sieg. The colour varies according to importer. But there may be small differences between different imports. Mine is an SC2 (Axminster C2-300). I'm not sure what the C3 is though (can't see one on Axminster).
!!!GOOD SHOW!!!
Having looked further at your video it seems the piece not supplied is the inner left hand circular piece.
WHICH !! WAS !! A ! PILE !! OF !! CRAP !!! ANYWAY !!!
Strange my sample of mini lathe exhibit problem unlike this one. This could be implementation but design problem.
Hi! Could you try to use Axial Ball Thrust Bearings..?
Yes.
Cheers
Who ever designed this did not simply forgot something, but intentionally did it to save pennies on parts and total weight.
Designed to work. Not very long.
good jobe, buat insepirasi salam dari indonesia
i sse - triumph of coefficient of STATIC friction over sliding friction
There should be a half round spring in the groove under the graduated dial that I don't see in your video.
Check out this video.ruclips.net/video/LLo6VMHzzuA/видео.html
@@claytonmusgrove8438 Yes, the spring is fitted, I just didn't show it in the video. It isn't relevant to the problem I was trying to address.
Basically the spring is not strong enough. If you loosen the gibs the spring is sufficient but then the slide wobbles.
these mini lathes , especially the cheaper one's come very ruffly put together as you now know. You have to do a lot of fine tuning sort a speak to get them running good. if you had bought a high end lathe , you wouldn't have to do anything to it . But the cheap ones you do. I bought a grizzly 90729 mill /lathe combo and still I had to do a lot of fine tuning to get things just right.
SAME !!! PILE !! OF !! CRAP !! DIFFERENT !! PAINT !!!
I frikkin hate my top slide, I wanna just throw it across the room! lolol
JUST !! GET !! SLEDGEHAMMER !!! ON !! IT !!!!
very well explained.
Probably a Chinese lathe. I would guess the the spacer piece isn't parallel or the male and female dovetails were not machined at the same angle!
Warum keine kugellager eingebaut?
Ich habe es einfach gehalten
First thing you gotta do is sand the ways flat. The top slide can be flattened on a piece of sandpaper laid out on a flat surface. Once that's flat(test by bluing and sanding to detect high spots) I glue sandpaper strips to the bottom of the top slide and reassemble the compound and tension the gibs down to point it barely moves and slide it back and forth by hand until you have a flat way surface. Now do the same for the cross. I've found that manufacturers do a good job on the bed where the carriage fits but terrible job on the cross and compound. You may also need to make new gibs or sand yours flat if they aren't too bent. Once done you'll find it doesn't lockup when you remove the slop. You won't have slop in one area and too much tension in another as well(my main problem).
Yes, something like that. The purist will say I should scrape them and that sanding will just embed abrasives in the ways. But with these cheap minilathes one probably doesn't need to be too careful. I did measure the top slide ways carefully with micrometer and dowel pins but could not get consistent results so could not decide what needed doing. Remaking the gibs is definitely desirable as the standard ones aren't really big enough.
imo less gib length is no problem.
You still have a lot of backlash there.
easier fix,put a set screw in the degree wheel .
Супер
I fixed mine by doubling the amount of gib screws
IS !! IT !! DAMAGED !!
??
Merkt der nicht wie sehr die Wackelt wenn er egal wo dreht🤨🥴
You bought a chinese lathe. So thats what you get.
EXACTLY !! ALL ;! THESE !! STUPID !! YOU !! TUBE !! TIGHT !! BEHINDS !!! ON !! HERE !!!
Brass gibs work much better
Do they? Why?
You keep saying left and right and confusing yourself and viewers... just refer to the movement as in and out and all confusion ends...no?
most lathes are terribly designed - it's amazing there hasn't been a major rethink in that department
THAT'S!! HOW !! PLANET !!! CHONGA !!! WINS !!!
PUT !! THE !! LATHE !! STRAIGHT !! INTO !! THE !! METAL !! SHREADDER !!!!!
WORK !! COMPLETE !! NOW !!!
poor processing and bad material
PLANET !!!! CHONGA !!! FIVE !!! YOU !!??? NILL !!!!
welcome to the word that copy every ting and does not know what they are doing and do not care as long they make money.... I did not had the problem with the dial, but ill did check my lathe an to my sup-rice it had the same problem. I am not looking op from this . But what I do not understand that if people find this out they are not reclaim this by there supplier and send the crap back. If it was a VW Atlas or similar the people were standing right away at the garage and started a big recall for that model. ( unfortunately I bought this price off crap from a good friend and not from a dealer) I do know that you get what you pay for, and that you can not make a perfect lathe for that money, but it does not mean that in this case the manufactures/copiers should take responsibility...