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Old 11-07-2016, 10:00 AM   #1
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Default AL320 Lathe Mods + Rebuild

Hi all,
I have finished rebuilding my AL320 lathe and found many 'chinese' issues along the way, so I thought I would provide some info about it. Seeing as this forum is the only place I found any worthwhile AL320 information and other people who own one.

First, the end result... before it gets dirty and messed up again


Paint is a hammer tone finish charcoal and blue

First ever mod was a tool holder and tray above the switch box


Second mod was a MT3 tool holder on the side

Originally it was 3 holders higher up on the side of the splash back panel, but I soon needed more space

Removing the half nut lever until needed I thought was a clever idea, removes risk of an accidental handle grab, and as I never cut imperial threads, I figured the dial was not relevant with my threading method


An annoying feature of this lathe was the power feed lever. It was too easy to move the lever too far past neutral, engaging the opposite feed and then crashing the tool into the work, especially when trying to finish a heavy cut or high RPM concerntration

I removed the detent ball and spring from an old 1/2" power bar and installed it into the lever, moving the lever back and forth many times revealed the arc and then a spot drill hole gives a positive neutral spot
(BTW in the apron parts drawing items 43-49 is the factory detent system for this, mine was set weak from factory and adjusting tighter still gave unfavorable results, I think it's too far away from the lever)

Later I Installed the digital caliper for the tailstock, if anyone paid attention to the rear dial, it counts to 69 not 70 and it doesnt count in metric


Somewhere in time the QCTP was installed, I milled the top of the compund off to lower it, I had trouble getting a good finish and rigidity during parting, surface grinding helped but I would like to make a new compund slide eventually.


I added an end stop for the compound slide, rotatable to 3 positions


On the subject of the compound slide, removing it lets me install the ball turning tool


The DRO was installed about this time, pretty standard stuff

1 micron cross slide scale = 0.002mm resolution on diameter

5 micron carriage scale = 0.005

Along with the DRO, I got rid of the absolute crap stand they offer, I made a frame to hold a large Roll Cab and made use of the all the storage space...\


Tooling in the top drawer, Chucks in the bottom


The new base is much wider and deeper giving a better stance, removing 90% of the harmonic vibration without needing to bolt it to the floor, 4 jaw work is much better now

The best upgrade aside from the DRO and Stand is the 3 Phase motor and single phase to 3 phase VFD... ooh yeah, soft start, Instant reverse, jog button, speed dial...

Sorry, couldn't fix rotation

Control Box


Oh and the Hour meter I installed since day 1, 330 running hours since new and counting


Lastly, the new change gear chart seeing as I removed the old one for repainting... thanks to Maryak for providing the spreadsheet here. I reformatted the sheet to merge all combinations in one block and to fit nicely on one A4 page

It also has a spot for the measured centre heights (@ Bed & Cross Slide)
And I will be laser printing and laminating a final copy at work tomorrow

So that's the extensive mods listed and as it sits now... I'll post some rebuild pics shortly...


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Old 11-07-2016, 10:59 AM   #2
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Lovely work B.

Even though I don't have one of these lathes, some of the ideas are generic, so can be used elsewhere.

It's nice to see people giving something back rather than keeping it to themselves.

John


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Old 11-07-2016, 11:46 AM   #3
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So, I didn't take a while heap of photos during the rebuild, but I'll show you what I got... or found...


Tearing it down...

Shortly after buying it, i opened the gear case to check if I was the proud owner of Chinese foundry sand mixed with oil... nothing major found, it was reasonably clean. I placed a neodymium hard drive magnet inside to catch metal shavings...

Then I noticed the gear alignment was terrible...


The shaft was actually installed backwards! there is a shoulder on the splined shaft and its just off centre. I didnt have the motivation to do anything about it at that time. I bought some decent spindle bearings, put them in the drawer and waited for the right time...

The right time was when I was starting a CNC spindle project and it just wouldn't cut a true shaft to save itself. I must have dislodged some Chinese burrs or swarf in the headstock mounting during a heavy cut. Over 100mm it was off by 0.2mm. Headstock alignment was needed and seeing as I went that far, I may as well go the whole hog...


Look at the sludge, magnet is full of filings


Laying it all out



Main Spindle


First Shaft from Motor Pulley


Second Shaft - Gear Selector Shaft


Third Shaft transfer to Spindle


Pulley Assembly


Gear Selector Forks


Putting it all aside in order and covering with a towel until ready to reassemble


All gaskets made from 0.8mm oil resistant paper, the OEM rubber gaskets swelled up terribly

So about this time, I chipped away at the inside and its amazing how much casting sand is left in there AND PAINTED OVER!!! Yep the paint is holding it to the walls. The upper corners especially, I spent a few hours just pecking and scraping and shaking out all the crap until I could get no more... I then cleaned up the oil delivery channels to the main spindle bearings, I filed a channel so it would flow into the bearings easier.

FYI - it is the gears picking up the oil, splashing it onto the roof, the oil dripping from the roof onto the outer edges of the top cover and flowing into the outer groove is all that luricates the Main Spindle bearings....


After painting the outside, I start installing the insides. Gear selector shaft installed the correct way round this time


Yep proper engagement this time


Selector forks and levers installed... Aah sh*t, the detents were drilled wrong to suit the wrong it was since new...


Hard to see, but even Hi/Low fork hits the casing before the gear is in line... No wonder it would pop out of Low gear on a real heavy cut...


Solution - trim a few mm off here

So to fix the detent issue once the gears actually managed to line up. I flipped the mounting flange upside down (thankfully it was 2 screw fixing and not 3) and installed the spring and ball, moved the gears back and forth full stroke 30-40 times revealing the arc and limits on the flange


New points centre punched


Spot drilled, notice the wider spacing this time



OK so that problem is now sorted... Rest of the install was straightforward


Onto the Leadscrew gearbox, ooh good they used thrust bearings, filthy but with a wash in kero and fresh grease they'll do just fine


I was OCD about the apron to carriage installation and didnt like how they weren't bolted flush... So I threw them on the Douglas 10.5" shaper I got a few weeks earlier. Was the shapers first job aside from a test cut to figure the thing out. Cool, I probably wouldn't have been able to mount it on my Mill Drill.


Oh yeah, this pulley was a real b*tch to get off, needed to use short bolts and nuts behind it to press it off. I suggest drilling and tapping 2x m8 threads on a 76mm diameter and wind it off with long bolts. There is a 6206 bearing installed in pulley with OD of 62mm and the inner diameter of small V groove is 90mm making the difference 28mm / 2 = 14 + 62 = 76
I lazily put some gear pullers on it at first and it just broke chucks off the larger groove (son of a b*tch), so I am using the small groove right now until I make a new pulley, but with a VFD I can take my time...


Next Post (tomorrow) will show my headstock alignment. Using Rollies Dads method and shims.
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Old 11-07-2016, 12:48 PM   #4
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Most enjoyable, thanks for this post, Mr Who.

How would you feel about putting a magnet in the oils sump?

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Old 11-07-2016, 02:04 PM   #5
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Look forward to see alignment,but what are all these gearwheels for when Yuo
use VFD?
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Old 11-07-2016, 07:54 PM   #6
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Very impressive undertaking. And always interesting to see what's under the hood of our machines. Look forward to the next installments. Thanks for taking the time to document.
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Old 11-07-2016, 09:13 PM   #7
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Quote:
Originally Posted by charlesfitton View Post
How would you feel about putting a magnet in the oils sump?
Any metal filings coming from gears meshing etc will eventually find its way to the magnet and stay there, avoiding the bearings

Same as finding detergent free gear oil - the detergent traps foreign objects and gunk in the oil (normally to head for the filter) detergent free oil lets it settle on the bottom, avoiding bearings.
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Old 11-07-2016, 09:15 PM   #8
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Quote:
Originally Posted by Niels Abildgaard View Post
what are all these gearwheels for when Yuo
use VFD?
VFD does not give optimum torque at all speeds.. best of both worlds, I have my favourite gear speeds to use
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Old 11-08-2016, 09:16 AM   #9
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So, using Rollie's Dad's Method, a pdf I found here

Starting out, I'm using a aluminium roller from a scrapped photocopier (CNC parts, and springs!.. lots of springs) the roller is made to high tolerances and smoothness. My 3 jaw chuck however, is China's 'finest' (came with the lathe)

Using the toolpost mounted plunger and a DTI on a magnetic base made testing quicker
Runout was 0.04mm at the chuck, zeroing the dials in the middle, and going to the other end, 250mm, it averaged out that shaft runout was 0.18mm.


My horizontal dial reached 0.34mm, but the vertical stayed true (-0.09 to +0.09). So I had to pull it over 0.25mm... time for some shims on the V groove to kick it over


Despite having sheets of shim stock on hand, an old set of feeler gauges has much more selection to choose from. I had used this set to tram the collumn of my Mill Drill previously

Cutting to shape and checking thickness...


An equal shim on diagonal opposites of the V groove leaves the vertical alignment alone but kicks the headstock to the side

Motor side of V here


Operator side back here

Bolting it down and testing it out numerous times to see how close I could get it, I ended up with 0.01mm over 250mm.

Mixing up the shims changed the vertical height quite a bit, even when the flat end of the head stock was bolted down to the bed...
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Old 11-08-2016, 02:19 PM   #10
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Bob,

I actually used the same method before I knew about Rollies dad when I restored and rescued a mini lathe.
I used aluminium foil as it was a lot thinner than shim stock that I had and managed to get the TIR to about 0.0005", which including skimming the back of the chuck as well.
It was a bit of a bother putting the shim in, trying it out then stripping down again until I had it right.

People don't seem to realise that with a little thought and effort, these Chinese machines can be got to perform like they were never expected to.

John


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