# Trading My Atlas For Sieg 7x14 - Bad Idea?



## CarlosA (Jan 16, 2016)

I moved to an apartment, and brought my Atlas 618 with me. Its been a good lathe but right now i`m dealing with the lead screw + half nut issues and being as expensive as it is i`m considering parting out everything and buying a new import 7x14 and a mini mill... I have slowly collected every accessory for the atlas except taper attachment. 

My other big issue is the countershaft and motor - these work fine in a garage where noise doesnt matter, but running the motor at 1725 rpm and having the belts and pulleys spinning creates a lot of residual noise and vibration.

I have prior experience with the 7x lathes. What does everyone think?


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## kd4gij (Jan 17, 2016)

I think in the long run you would regret  giving up the 618


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## Gunner (Jan 17, 2016)

If motor drive noise is the issue, you could consider converting it to a variable speed DC motor.


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## ogberi (Jan 17, 2016)

Unless you're having accuracy issues with the Atlas, I'd hold onto it.  Especially since you've said you have acquired darn near all the accessories.  If the belts are making too much noise, consider changing to a link belt.  I use on on my Atlas horizontal mill, and aside from a little squeak-buzzing, it's very smooth and quiet.  Replacing the belts with new might also take care of the problem.   You might also want to consider isolating the motor with rubber mounts.  Some rubber between the lance's stand and the floor may also go a long way towards reducing the noise.   I'm not sure you would be happy with an import, but I could be wrong.  Is there anybody local to you that you can go put hands on one?  Maybe sneak a chunk of aluminum, and a cutting tool into the nearest Harbor Freight, grab one of their extension cords and give the display model a go.  Until you get caught, that is.


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## great white (Jan 17, 2016)

Here's my 10f running on a variable DC motor as a noise ref:






It used to make lots of metallic clanking noises before the DC motor. Nearedt i cant figure is the single phase ac motor wasnt smooth in producing power pulses. It's nearly silent now by comparison. Even back gears have lost that metal "ringing" sound.

It buzzes a little bit, but that's only when its regulated down really slow. Once up to any real working speed, you either can't hear it buzzing or it disappears into the rest of the noises.

The ac motor was quieter than the DC motor but the whole machine is quieter running on the smoother DC motor. 

I went with a higher end Baldor tefc motor too so that might be part of it compared to the DC motor. I shopped around and have about 200-250 bucks total in the motor (ebay grab on an auction nobody was watching i guess) and the cycletrol speed control.

Someone else might be able to give you some perspective on a 3 phase ac motor and a vfd.

Keep in mind I don't have either of the machines you're looking at, but it seems to me if you have your atlas all kitted out with the accessories it might be a better idea to put a few bucks into making it quieter rather than starting over with a new machine that might have the same (or similar) noise issues....


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## CarlosA (Jan 17, 2016)

Thanks for all the replies - I've done all of the above except add a DC motor, either that or a VFD is high on my list. The two issues I currently have are:

Buying a new leadscrew and half nuts will be $200+ 

Buying a new motor and control will be $200+ 

Making a new delrin tumbler gear will quiet down the gear train quite a bit - will do that once the lathe is running again. 

So these new costs exceed a new 7x lathe - selling all of my accessories would cover misc tooling and a mini mill, lol. 

I am currently attempting to make new half nuts, but it's not going well with the tiny single point tool inside a .427 hole.


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## CarlosA (Jan 17, 2016)

@great white

Thanks for the video - I have been watching some of these dc motors and controls on eBay and will eventually get one. If not for the lathe I'll use it for something.


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## CarlosA (Jan 17, 2016)

I'll add before someone says it: Yes, I'm on the lookout for a treadmill, but so far fitting one in my VW rabbit without making a scene has been a problem. 

I get several notifications a day during weekends of free treadmills on Craigslist - good tip for those of you looking. Ask me if you need help setting it up.


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## ogberi (Jan 17, 2016)

I had issues on a part I made, ACME internal threading in a .75" hole.  The solution I found was to make a threading tool shank that was just smaller than the bore, and to grind the cutter, then cut it off short enough that it barely, barely stuck out past the required thread depth.  The cutter was mounted 90 degrees to the shank, secured with a grub screw.  I had to advance the tool a time or two, and fiddle with it to touch off (lathe off, rotate spindle by hand until it squeaked), but that gave me the most support for the cutter, without having to spring for an expensive ACME tap.   Maybe Delrin for the half nut?

Edit - As far as fitting a treadmill into the Rabbit (I've had a few of those), the quick solution is a battery powered SawZall and some good quality blades.


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## CarlosA (Jan 17, 2016)

ogberi said:


> I had issues on a part I made, ACME internal threading in a .75" hole.  The solution I found was to make a threading tool shank that was just smaller than the bore, and to grind the cutter, then cut it off short enough that it barely, barely stuck out past the required thread depth.  The cutter was mounted 90 degrees to the shank, secured with a grub screw.  I had to advance the tool a time or two, and fiddle with it to touch off (lathe off, rotate spindle by hand until it squeaked), but that gave me the most support for the cutter, without having to spring for an expensive ACME tap.   Maybe Delrin for the half nut?
> 
> Edit - As far as fitting a treadmill into the Rabbit (I've had a few of those), the quick solution is a battery powered SawZall and some good quality blades.



Good ideas .. I could take my hand I hack and an inverter!

As for the acme - in this case it is 1/2x16 - very non standard and small enough that grinding the tool is a pain. I will definitely be trying out delrin - the shape of them is complicated (for me) but I think you are right - easier to machine and quicker to make a new one when I screw it up.

Edit to add: in this case I'd absolutely pay the cost of the half nuts for a tap - if it meant I could make future sets. On that note, thoughts on converting to a more standard 1/2x10 leadscrew? I'm ok with not being able to read the worn out gear chart - but i guess I'd give up the slowest feeds.


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## CarlosA (Jan 17, 2016)

Well,

Delrin as a material works great - was easy to cut the threads and see where I have to improve the relief on the tool. It was scary because the half nuts do try to disengage often - I found that putting some force on the hand wheel/rack helps it along. This photo is of a nut I just whipped up as a test.


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