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Ronsul

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Hi everyone , thanks for accepting me into the group. Ive been messing about with all things mechanical my whole life (mostly motorcycles) and wished i had a lathe just about every week for the last 40 years ! finally took the leap of faith and purchased a H&F AL320G . Not knowing anything about them i just naively thought oh well theyre probably all similar . After messing about with it for a few hrs i now see the shortcomings of this model. Quality is fairly poor with things like the hand wheels cant be tighten up without jamming the slides,the gears supplied are all very poorly finished and dont fit the shafts etc. anyway enough grumbling and looking forward to the steep learning curve.., Ron
 

Ronsul

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Being a novice on a lathe, please excuse my ignorance(AL320G ),can anyone explain to me why the thread chasing dial on the feed shaft turns ok when the half nut (screw cutting engagement)is disengaged but not when the half nut is engaged , it does work when i engage the other 3 position lever that engages the cross and longitudal feed ,has a neutral position ,but using this feed the tool travels about 3 times the speed . with only the half nut engaged the travels at the correct speed for the thread gears i have chosen. i have tried using reverse to maintain tool position but not very successful. im sure i am missing something here..
 

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HCNZ

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Hi Ron, I also have an AL320 lathe, the thread chasing dial should only turn when the half nut is disengaged, when the half nut is engaged the carriage (and thread chasing dial) will move along the lathe bed at what ever thread cutting speed you have set, because the thread chasing dial is moving along the thread it won’t turn. Hopefully that makes sense. The AL320 isn’t the best lathe but it’s very versatile and capable for the price and I get a lot of use out of mine. Don’t forget AL320 with a metric lead screw the thread chasing dial will only work for cutting metric threads and it won’t work for every metric thread pitch (M12 being the main thread the dial won’t work on) I’ve made a spreadsheet with the different thread pitches and engagement points I can try and find if you’re interested. I’ve also made a second thread chasing dial with a different gear ratio to cover M12 and a few other threads.
 

Ronsul

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id love to see the spreadsheet,.i only need metric threads , what i dont get is, what use is the dial if you cant use it when cutting a thread ? and why does it work when using the longitudal and cross feed that travells much faster and cuts a thread about 1/3 of what the gears are set for.?
 

HCNZ

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You only need the thread chasing dial when the half nut is disengaged so you can re-engage the half nut in the same place on the lead screw, so when you take the next cut the cutting tool lines up with the last cut. The half nut is driven by the thread on the lead screw and is used for thread cutting. The longitudinal and cross feed is driven by the groove that runs the length of the lead screw and is used for power feed not threading. This reduces wear on the lead screw threads and gives a further reduction in gearing that’s needed for power feed. When the longitudinal and cross feed is engaged the carriage isn’t moving at 1-1 with the lead screw thread so the thread dial will turn. Hopefully that makes sense, I’ll try and find the spreadsheet tomorrow.
 

deeferdog

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Hi Ron, it's much easier to simply reverse the motor and leave the feed engaged until the thread is finished. I seldom use the chasing dial any more. I have the AL250 lathe and find it a very good machine for the money. I think you will find the same with the AL320 over time, most of the problems can be sorted out and the end result will serve you well. H&F are a good company, I can only speak as I find but they have backed every machine I have brought from them over the years, if you have major issues with the lathe contact them. Cheers, Peter.
 

HCNZ

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Attached is a picture of the chart I made for the AL320 thread chasing dial, I’m not sure if I could have made it any more confusing if I tried. The standard thread chasing dial has a 20 tooth gear but I have also made another dial with a 21 tooth gear to cover the threads the standard dial doesn’t do, this is not at all necessary but I got carried away. Basically just pick your thread and if there is a number in the box you can engage the half nut at that point in the chasing dials rotation. Some thread pitches the half nut can be engaged at any point. I’ll try and find the spreadsheet version of the chart if you want it. Not sure if this is useful or just confusing.
 

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joco-nz

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Ron - like HCNZ I had some extra collateral.
1. A spreadsheet of all the change gear combinations for TPI and Metric (excel format from an Aussie member)
2. A spreadsheet of gear cutting using the chaser dial I did. Super similar to HCNZ’s version and using the same concept. In openoffice /LibreOffice format. Also a PDF version.

i cant upload the spreadsheets so here are google drive links:
1. Excel file
2. Libre Office file

Cheers,
James.
 

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Ronsul

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Hi Ron, it's much easier to simply reverse the motor and leave the feed engaged until the thread is finished. I seldom use the chasing dial any more. I have the AL250 lathe and find it a very good machine for the money. I think you will find the same with the AL320 over time, most of the problems can be sorted out and the end result will serve you well. H&F are a good company, I can only speak as I find but they have backed every machine I have brought from them over the years, if you have major issues with the lathe contact them. Cheers, Peter.
what is the best thing to disengage to stop the feed while cutting ? motor stop, cross/longitudal feed lever,or leadscrew fwd/rev gear selector ,both of them have a neutral position. also is it ok to engage long/cross feed whilst leadscrew is turning? i know you cant engage the leadscrew while motor running
 

SmithDoor

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Welcome to group.
New to lathe, most start small using ruler and work up to the mic's.

Dave

Hi everyone , thanks for accepting me into the group. Ive been messing about with all things mechanical my whole life (mostly motorcycles) and wished i had a lathe just about every week for the last 40 years ! finally took the leap of faith and purchased a H&F AL320G . Not knowing anything about them i just naively thought oh well theyre probably all similar . After messing about with it for a few hrs i now see the shortcomings of this model. Quality is fairly poor with things like the hand wheels cant be tighten up without jamming the slides,the gears supplied are all very poorly finished and dont fit the shafts etc. anyway enough grumbling and looking forward to the steep learning curve.., Ron
 

joco-nz

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what is the best thing to disengage to stop the feed while cutting ? motor stop, cross/longitudal feed lever,or leadscrew fwd/rev gear selector ,both of them have a neutral position. also is it ok to engage long/cross feed whilst leadscrew is turning? i know you cant engage the leadscrew while motor running
here are some options that I used.
1. I started out running at a slow speed for threading and stopped the motor at the same time as twisting the cross slide back to disengage the threading tool. Then reversed the spindle to feed back to the start. Suggest you search youtube for threading instructional videos. There are a lot.

2. Once I sorted out how to use the thread chasing dial I started to use that for the threads it covered. It meant I could stop the saddle travel on a dime.

3. Then learned about threading running the spindle in reverse with the threading tool running away from the chuck. Very low stress, especially when threading to a should. Your threading tool either has to be on the back side of the work (ok for short threads) or in its normal position but upside down as the spindle is in reverse. Joe P on youtube demonstrates this technique.

cheers,
James.
 

kiwi2

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Hi,
There is a way of stopping the cut if you have a thread dial by disengaging the leadscrew, even if you are cutting a metric thread on an imperial machine (or vice versa). The method is as follows:

After setting the tool to cut the correct depth, start the lathe in the forward direction and when the thread dial reads 1, engage the thread nut.
When the tool has advanced to the end of the thread, disengage the half nut and turn the motor off. Do it without delay so that the thread dial rotates less than 1 full turn.
Withdraw the tool to clear the work.
Start the lathe in reverse and when the thread dial reads 1 engage the half nut.
Run the lathe in reverse until the tool clears the work.
Turn the lathe off but leave the half nut engaged.
Set the tool to the new depth and start the lathe in the forward direction.
Repeat till the thread is cut to size.

This method is useful because disengaging the half nut stops the tool a lot quicker than waiting for the lathe to run down giving a more accurate stopping point.

The method is shown on YouTube here:


Regards,
Alan
 

clockworkcheval

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Hi, I have a Schaublin 102 VM lathe, with the massive leadscrew central underneath the bed. This is nice but makes a thread chasing dial impossible. I use several options in threadcutting 1) very low speed. Regular speed range is 80 - 2000 rpm, but with the frequency regulator on this can be extended to 10 - 3000 rpm. 2) my leadscrew has a 4 mm pitch. Thus for pitches that divide into 4, like 0,5 - 0,8 - 1 - 2 mm I can disengage the halfnut any time without penalty. 3) other pitches I cut by retracting the tool and reversing the spindle simultaneously without disengaging the halfnut. At 10 rpm this is doable even for a slow person like me.
 

rodw

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Hi Ron. I had an AL320G which I bought new. I really think its a good solid and accurate lathe for the price. Its nice and heavy and has a good sized spindle. You can spend a lot more on a lathe with the same size spindle bore and swing. It really only has two limitations. It uses change gears, not a gearbox and it does not have a DI-4 removable chuck. But I was able to fit a 5C collet chuck and still got accurate work. The change gears do make it a bit fiddly to set up for threading. But I've only ever had to cut about 3 threads in my life. All on the 320G. I never used the dial chaser, just reversed out. Dealing with backlash is part of the journey, I never found it a problem. One of my mates sold it to a random guy in Hare and Forbes one day. I went to buy a AL336 but came home with a second hand 3 phase version of an AL960B with coolant and DRO instead. It is made in Taiwan and a cut above these Chinese ones but you are talking about a $7k lathe.

Just focus on having fun. You won't really have any limitations with it. There is a thread of mine called Rods Aussie Shed which you might pick up some ideas from it. I know Joco did when he got going. Now I think he knows more than me!
 

Quickxb

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Gday Ron, I also have the AL320G and at first thought it was a bit of a pos but with a few mods and some time learning the machine you can get good results, at least for a back yarder. There are plenty of posts about modifying them so do some searching. The qctp is a worthwhile add and I would suggest HSS instead of carbide, another thing to add is some locks for the carriage, cross slide and compound. A stop for your cross/carriage motion lever is aslo highly advised. I don't have pics to upload but I can get some if it will help. Definately research the threading ideas if you plan to do much of it, I actually pulled my dial chaser away from the lead screw as I don't use it and it saves wear and tear on the screw (I probly should just throw it in the bin it's useless to me)
 

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