# My DIY Atlas 618 milling attachment



## WCraig (Mar 10, 2019)

Hey!  I made diy milling attachment for my tiny Atlas 618 lathe!!

I don't have a mill and acquiring one is not in the cards for the foreseeable future.  But then I ran across Harold Hall's amazing website and the idea of using an angle plate to enable the compound to move a vise in the vertical direction.  So I did that:




Since I'm a newbie, there were a couple of missteps and a piece that had to be remade.  I already had the vise which had 3/8-24 mounting holes on the bottom.  I had to add an extra set of mounting holes to get a better range of travel. 

Here's a sort of 'exploded' diagram:




I know this isn't a real mill.  I know I'm not going to be taking heavy cuts and I plan to mostly use it with aluminum and brass.  Hopefully it will work OK for that.

It isn't hard to set up or tear down.  Two allen keys are all that is necessary to mount it.  A 1-2-3 block in the vise helps to get it pretty square to the spindle.  I need to buy proper end mill holders.  I see Shars has some for $12 USD per size.  

All in all, this has been a fun project.  Hopefully I'll get some use out of it.  First thing I want to try is a carriage stop.

Craig


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## thomas s (Mar 10, 2019)

Nice job Craig.


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## WCraig (May 20, 2019)

My first attempts at cutting a simple part in mild steel were abject failures.  The "Y axis" (which uses the lathe's compound) was moving on its own while I was advancing the X axis (the lathe cross-slide).  The resulting slot was crooked and well off the planned line.  Also had a lot of vibration and cutter was grabbing the work and self-feeding (X).

I decided that I needed to lock the gib screws as best I could for the Y axis whenever possible.  And tighten the X axis gib screws much more than I do for normal turning.  Tightened the belts somewhat so it wasn't so easy to stall.  Moved the mount for the vice so the fixed jaw would come right up to the centre line of the cutter.

I'm now much happier with the result:




This is straight from the machine; no deburring or filing.

Remaining issues:
1) I wanted to start with a pass down the middle of the slot.  However, the cut was 10-15 thous above the line.  I know I've taken up the lash in the compound so I'm not sure why this is happening.  In fact, I had already used this set up to drill the "Q-sized" holes at either end of the slot.  There was apparently no slippage during that and I left the Y locked when I changed over from the drill to the end mill.

2) The connection to the cross slide slipped a couple of times causing the vise to rotate out of square to the end mill.   Atlas designed compound to lock with screws at 120 degrees angle.   I used 3 screws at 90 degrees and I think that is less effective.  I don't see any realistic way to switch to 120 degree spacing as the piece is square.  I will double-check the locking pins in case they weren't oriented the right way.  

The bottom line is that until a well-equipped small milling machine drops into my lap, I now have at least some basic machining capacity.

Craig


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## Rooster (May 20, 2019)

Greetings Craig, realize that flex is the enemy. Your cutter is a long way out, you should get a mt2- 3/8" endmill holder. I have an Atlas milling attachment for my 618 and i make sure all gibs are snug.Lots of little bites and sharp cutters is the way to go. Have fun.


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## wa5cab (May 21, 2019)

Craig,

One should never use three set screws at 90 deg.  Nor for that matter, three at 120 deg.  Two at 90 is almost as good as two at 120.  The basic idea is that both set screws should be forcing the inner part against the far side of the hole in the outer part.  The reason not to use any configuration that has set screws on opposite sides of the outer part is that the inner part is only locked and supported by the tips of the set screws, not by part of the fixed part, whether inside or outside.


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## WCraig (May 21, 2019)

Rooster said:


> Greetings Craig, realize that flex is the enemy. Your cutter is a long way out, you should get a mt2- 3/8" endmill holder. I have an Atlas milling attachment for my 618 and i make sure all gibs are snug.Lots of little bites and sharp cutters is the way to go. Have fun.


Thanks!  That's an older picture in the first post.  I did get an end mill holder:






						Precision End Mill Tool Holder Morse Taper 2 3/8"
					

Shars Tool




					www.shars.com
				




Craig


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## WCraig (May 21, 2019)

wa5cab said:


> Craig,
> 
> One should never use three set screws at 90 deg.  Nor for that matter, three at 120 deg.  Two at 90 is almost as good as two at 120.  The basic idea is that both set screws should be forcing the inner part against the far side of the hole in the outer part.  The reason not to use any configuration that has set screws on opposite sides of the outer part is that the inner part is only locked and supported by the tips of the set screws, not by part of the fixed part, whether inside or outside.


Thanks @wa5cab I'll try that next time.

Craig


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## markba633csi (May 21, 2019)

Craig do you have a drawbar arrangement in the spindle?  You don't want the cutter assembly to come loose
Mark


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## WCraig (May 21, 2019)

markba633csi said:


> Craig do you have a drawbar arrangement in the spindle?  You don't want the cutter assembly to come loose


Indeed I do.


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## Johnahake (Oct 3, 2019)

Cool idea! Can you swivel both the compound the angle plate and the compound to vise? 

Would it be better to reverse to orientation of the compound, so it remains vertical, and the vise can swivel off of it?

Im a noob and want to make something similar, any advise relating to this would be appreciated!!

John


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## WCraig (Oct 4, 2019)

Johnahake said:


> Cool idea! Can you swivel both the compound, the angle plate and the compound to vise?
> 
> Would it be better to reverse the orientation of the compound, so it remains vertical, and the vise can swivel off of it?
> 
> I'm a noob and want to make something similar, any advise relating to this would be appreciated!!


Yes, you can set angles in both directions to be able to mill some really funky ramps!  However, in both cases you have to loosen the fasteners to adjust the angle so it is tough to get a really precise angle dialed in.  

I'm not sure how the compound could be re-oriented.  The advance knob would have to be between the bed ways?

When I was scratching out the design, I looked at the travel available with the compound.  I then tried to position the vise so that the fixed jaw could come up to the center line of the cutter and down towards the bed as far as possible.  

Note that I got a mill/drill a couple of months ago and I don't see myself using this anymore.  But anything is possible.  This setup can hold stock in ways that would be impossible on a normal mill.  Maybe I'll have a reason to mill a feature into the end of a piece that is too long to fit under the mill's spindle?  In any event, it was a fun project for a rookie and I learned a lot doing it.

Craig


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## Janderso (Oct 4, 2019)

Nice job Craig!


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## yendor (Oct 4, 2019)

Looks like Necessity the MOTHER of invention just gave birth to another useful widigt.


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## Johnahake (Oct 4, 2019)

WCraig said:


> Yes, you can set angles in both directions to be able to mill some really funky ramps!  However, in both cases you have to loosen the fasteners to adjust the angle so it is tough to get a really precise angle dialed in.
> 
> I'm not sure how the compound could be re-oriented.  The advance knob would have to be between the bed ways?
> 
> ...



I guess when i said reorient the compound, i have seen other similar designs where the t-slot of the compound attaches to the 90 degree plate, and the base of the compound is used to attach the milling vise.

I suppose your way gives more possible configurations... i am wondering if you will need to rotate the compound anywhere but vertical.

Because you could always rotate the vise, and thus the part, to achieve any desired angle. Therefore, you would never need to tilt the direction of travel...

I guess it would make more sense if i could get my hands on it and try different setups. Like i said i am kind of a amateur, so im sure there is a setup where you would need to pivot both.

I will be making my own ‘diy compound milling attachment’ in the next week or so. I will post photos if i remember to take them.

Any sources for endmill holders, or is Ebay the best bet?


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## savarin (Oct 4, 2019)

Johnahake said:


> Cool idea! Can you swivel both the compound the angle plate and the compound to vise?
> 
> Would it be better to reverse to orientation of the compound, so it remains vertical, and the vise can swivel off of it?
> 
> ...



You might be able to get some ideas off this one.








						A Vertical Slide For A 9x20 Lathe
					

My first vertical slide was a bit small in what it could hold so I have decided to build a larger one. It should look something like this (but not in these colours:grin big:)  I faced and edged a chunk of hot rolled scrap for the front plate. I will drill and thread a matrix of holes in this for...




					www.hobby-machinist.com
				



Its been a real life saver for me.


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## WCraig (Oct 7, 2019)

Johnahake said:


> Any sources for endmill holders, or is Ebay the best bet?



I went with a few from Shars:






						Precision End Mill Tool Holder Morse Taper 2 3/8"
					

Shars Tool




					www.shars.com
				




OTOH, there is an issue with runout on the morse taper of my 618.  I'm still trying to track down the source and determine if I can fix it.  It may be as simple as needing more preload on the bearings but I haven't had a chance to look closely.

Craig


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## WCraig (Oct 7, 2019)

Johnahake said:


> I guess when i said reorient the compound, i have seen other similar designs where the t-slot of the compound attaches to the 90 degree plate, and the base of the compound is used to attach the milling vise.


Ahh, I think I see what you mean now!   It never crossed my mind to design it with the T-slot facing the tailstock--might be an improvement.

I think the key thing is rigidity--this contraption is not very rigid!!  I have mechanical attachments (threaded fasteners) between the vise, adapter plate, angle block and cross-slide.  Plus the further the vise is from the centre line of the compound, the more leverage it has.  All of that contributes to poor rigidity.  If you can work out a design that gives better/fewer mechanical attachments and/or less leverage, then you'll get a better overall result, I think.  One possibility might be to use a much larger angle block and make it face the tail stock rather than the head stock?  The bigger plate might impact cross-slide travel, too.

BTW, I had thought that I might fixture parts right onto the angle plate for milling.  I can drill and tap holes into the angle plate to secure the part if need be.  That could really improve rigidity in some cases but gives up "Y" axis positioning.

Craig


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## JRT (Oct 7, 2022)

Hey, I have a question... what size are these belts (looks like 3L) and do you have rubbing on the spindle lid where the belt is near the top at the rear of it or on your counter shaft where it passes under the cross member (part of the casting) before the pulley? I'm having the hardest time figuring out something that seems so simple. So frustrated, ANY help would be so appreciated. Thanks. -John


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## WCraig (Oct 8, 2022)

@JRT I used a segmented belt (aka link belt) between the countershaft and spindle so I just made it as long as needed.  The length you need depends on where you mount the countershaft assembly relative to the headstock.

3L belts should sit down in the grooves of the pulley and thus not rub on the cover.  

HTH

Craig
BTW, I sold the lathe this year so this is all from memory.


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## JRT (Oct 8, 2022)

Thank you Craig, all this time and I think I finally figured it out! I went back to it, ut the link belts back on and under tension and now they sit low enough to clear! Thank you. -John


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