Need Help!- How do I make threads on my Sieg C4?

[Blakelidge]

Hi,

Bought my Lathe a couple months back from ChesterUK. Amazing really, I got it for 699ukp, but I see it's now 1060ukp, anyhow. I can confirm it is a fantastic machine and now I have all my shiny cutters and stuff turning out components is really enjoyable.

Some may recall (if you saw my previous post) that when I got the machine, one of the bolts that holds the gear that connects to the leadscrew was snapped, granted it took Chester a goodly while to source a replacement, but they were nice to deal with so I'm not whining. Essentially, this meant that until last week when the parts came, I was unable to even try threading anything, however, despite trying this last few days I am unable to grasp the process for cutting threads and I wondered if anyone is familiar with this that might be able to help?

I have seen the threading guide on mini-lathe com but he refers to a "dial gauge" and my C4 does not have one, also, I am confused by how I should orientate the cutter in relation to the work, I understand I should offset the way by around 30 degrees and advance the tip along this plane on each pass so only the leading edge of the cutter does the work, but however I try, the outcome is horribly raggy. I am sure I did see a guide somewhere before specific to my lathe, but I can't find it on the net anywhere.

Any help appreciated

[MrWild]

yes, the compound is set at EXACTLY 30*, not "around 30*. Then the tool, bit is ground so you have an EXACTLY 60* point. To make sure it is exact, you need a threading tool setting gauge. You also need to make sure the cutter is just a ew thousands below the center o your part. Too high is bad, and too low is bad. I you don't have a threading dial, the safest way to thread is to stop the lathe as you near the end of the cut. Back off the Z axis and run the lathe in reverse while leaving the threading lever engaged. Doing this will make sure you don't lose your starting point. Never feed the Z past your Zero reference to increase a cut (you did zero out the Z and compound at the start of your thread cutting, right?), ALWAYS feed in with the compound.

[kawazuki]

Originally Posted by MrWild yes, the compound is set at EXACTLY 30*, not "around 30*. Then the tool, bit is ground so you have an EXACTLY 60* point. To make sure it is exact, you need a threading tool setting gauge. You also need to make sure the cutter is just a ew thousands below the center o your part. Too high is bad, and too low is bad. I you don't have a threading dial, the safest way to thread is to stop the lathe as you near the end of the cut. Back off the Z axis and run the lathe in reverse while leaving the threading lever engaged. Doing this will make sure you don't lose your starting point. Never feed the Z past your Zero reference to increase a cut (you did zero out the Z and compound at the start of your thread cutting, right?), ALWAYS feed in with the compound.

Once the spindle is stopped you note the reading on the 'X' axis / cross slide or zero it and back it out a complete turn of the handle (for ease of memory) - hit reverse switch -with the threading half nuts still engaged - and go back to in front of the thread start. Advance the compound whatever DOC your taking and start spindle in forward direction again and repeat ad infinitum until thread is done!

Its a bit boring but you must follow the routine - its easy to hit reverse before winding out the cross slide and screwing up the thread completely - usually just as its nearly complete on a complicated part !

Best of luck

[Geof]

Mr Wild writes: Back off the Z axis and run the lathe in reverse while leaving the threading lever engaged. but I am pretty sure he means back off the X axis.

To learn lathe threading get some material that is easy to work with such as brass; this is also soft so when you do something wrong you are less likely to destroy your tool.

As suggested get a thread gauge for grinding your tool, here is a Wikipedia page with a picture;

http://en.wikipedia.org/wiki/Center_gauge

The Wikipedia page also calls it a center gauge and in can be used to set your tool on center. Set your tool as close as you can to being on center by eye; now very carefully pinch the gauge (or any thin straight metal) between the tool and the work and look at it from the end of the work. If the tool is above center the top of the gauge will lean in toward the lathe centerline and out if it is below; you want slightly out by up to 5 degrees.

Set the compound to 29 degrees not 30; using 29 means the threading tool cuts primarily on the leading flank but takes a minuscule skim on the other flank to avoid leaving striations from the infeed.

With the tool just touching the work, pinch a bit of paper to check this, set the cross slide dial at zero and the compound dial at zero. Now back off the cross slide slightly.

Now for the tricky parts; draw a line on the work where you want the thread to end.

Move the carriage back so the tool is past the end of the work, set the machine to go really slow and engage the half nuts.

Notice I have not said anything about advancing the tool; you are doing some dry runs.

When the tool is in line with the mark on the work quickly rotate the cross slide out while turning the machine off; it will coast a little bit but not much.

Reverse the machine until the carriage is past the start point then forward to the start point to take out all the backlash; you can do this by hand just rotating the chuck. Bring the cross slide back to its original setting and practice dry runs a few times.

For the actual thread cutting the only difference is you advance the compound slide maybe .01mm and bring the cross slide to the zero mark that places the tool right at the work. For each cut the cross slide is what retracts the tool and the at the start of the next cut the compound is used to go slightly deeper.

[Blakelidge]

Thank you for your replies, so cool that people take time out to help others, maybe the World aint so bad as they make out on the news eh?

Well, I'm working in aluminium so that's pretty soft. Firstly, I trust I am getting my cogs in order?, looking in the gear end of the lathe, I take gears A,B,C,D with "A" being the uppermost and "D" being the lowest ("D" is fitted on the end of the leadscrew)

Assuming I am making the right gear locations, I set them up according to the thread-pitch lable printed on the lathe housing

Chuck my piece and face it to ensure it is true ( a 1" piece of rod about 3" long)

I agree with the 29 Degrees for the compound (not that I know, it's just that's what it said on mini-lathe.com) The compund is normally set transversely I.E its long edge runs parrallel to the bed of the lathe? To set the 29degrees, I loosen the two small hex bolts and rotate it CLOCKWISE until it reads 29 on the scale?

My next puzzle is this: On Mini-lathe.com he shows this photograpgh: [IMG][/IMG] this clearly shows the compound orientated not parrallel to the bed, but turned until its handle is facing towards the operator, albeit offset clockwise to 29 Degrees and with the cutter and toolpost mounted parrallel to the bed of the lathe, is that the correct way to do it? If so, no wonder I'm messing up, so should I set my machine as shown in the image?

Also, thanks very much for pointing out that I should back off the cutter PRIOR to reversing back to the beginning of the thread, I abviously made the wrong assumption that the cutter would have no work to do as it had cut on the forward pass already, but I did notice when reversing that the cutter was making a horrible chattering noise, so I now understand that I must back of the cutter (using the handle of the compound) prior to hitting reverse. I'm off to have another go, fingers crossed.

Thanks again
Dave

[kawazuki]

Your second description sounds how I do it - here's a piccy to explain?

[Blakelidge]

Thanks,

Cuts great now, suprising how easy it is once ppl help to show you how, had another night bashing away and finally got it cracked I think.

One odd thing though, seems whichever way I arrange the cogs according to the table, it will only cut very fine threads (pitch 1mm at most I would guess) even though my leadscrew seems to be spinning pretty quick even with the motor set at 100rpm. According to the table printed on the lid of the machine, setting A to 45, B to 120 and C to 30 that should give me a 3mm pitch, scratching my head again now, might buy some Araldite and just stick stuff together, seems an easier option.

[kawazuki]

Originally Posted by Blakelidge Thanks, Cuts great now, suprising how easy it is once ppl help to show you how, had another night bashing away and finally got it cracked I think. One odd thing though, seems whichever way I arrange the cogs according to the table, it will only cut very fine threads (pitch 1mm at most I would guess) even though my leadscrew seems to be spinning pretty quick even with the motor set at 100rpm. According to the table printed on the lid of the machine, setting A to 45, B to 120 and C to 30 that should give me a 3mm pitch, scratching my head again now, might buy some Araldite and just stick stuff together, seems an easier option.

You are using the threading half nut engagement lever on the front and not the carriage travel lever on the side?. The threading one is normally upright and turned clockwise to engage. the other one runs the carriage left and right and cross slide in and out.................I made the same mistake - poxy useless chinese manual!

[Blakelidge]

HAHAHAHAHA - what a prat I am, yep, I'm using the half-nut feed handle. I have the "useless chineese manual" here in front of me and I can see there is another lever on the front face of the carriage, I can honestly say I have never noticed it on the machine itself, I'm just off to the basement now to check it exists.

Red-faced and ashamed. In my previous role as computer tech support, I used to moan about customers who refused to RTFM (read the flippin manual) but I feel a little exonerated in this case as I have RTFM but there just is no mention in there of that handle, in fact, in the "Features" section that shows a picture with each component labled, it does not even lable that handle at all.

Thank you, your help is really appreciated.

P.S. I also just now found a link to a MUCH BETTER manual for the C4 and Mill attachment - http://www.axminster.co.uk/article-D...ds-manuals.htm it's a PDF contained in "Metalworking"

Cheers
Dave

[kawazuki]

Agreed - its a slightly better manual but not as good as some our American cousins get from their vendors.......and no they haven't cottoned on to the C4 yet so they haven't anything better! There are some interesting threads re the C4 on the Chester Forum - my trials and tribulations!

[Blakelidge]

Hi all,
Just a quick update on this. I purchased an internal and an external Glanze indexable threading bars (from Chronos) they cost around 20ukp each, about 32 usd I think. They arrived quick and work beautifully.

I,ve now made a few threaded items and still improving but generally they all work well as threads. Thanks again for all your help

Regards

[garagefela]

Originally Posted by Blakelidge Thank you for your replies, so cool that people take time out to help others, maybe the World aint so bad as they make out on the news eh? Well, I'm working in aluminium so that's pretty soft. Firstly, I trust I am getting my cogs in order?, looking in the gear end of the lathe, I take gears A,B,C,D with "A" being the uppermost and "D" being the lowest ("D" is fitted on the end of the leadscrew) Assuming I am making the right gear locations, I set them up according to the thread-pitch lable printed on the lathe housing Chuck my piece and face it to ensure it is true ( a 1" piece of rod about 3" long) I agree with the 29 Degrees for the compound (not that I know, it's just that's what it said on mini-lathe.com) The compund is normally set transversely I.E its long edge runs parrallel to the bed of the lathe? To set the 29degrees, I loosen the two small hex bolts and rotate it CLOCKWISE until it reads 29 on the scale? My next puzzle is this: On Mini-lathe.com he shows this photograpgh: [IMG][/IMG] this clearly shows the compound orientated not parrallel to the bed, but turned until its handle is facing towards the operator, albeit offset clockwise to 29 Degrees and with the cutter and toolpost mounted parrallel to the bed of the lathe, is that the correct way to do it? If so, no wonder I'm messing up, so should I set my machine as shown in the image? Also, thanks very much for pointing out that I should back off the cutter PRIOR to reversing back to the beginning of the thread, I abviously made the wrong assumption that the cutter would have no work to do as it had cut on the forward pass already, but I did notice when reversing that the cutter was making a horrible chattering noise, so I now understand that I must back of the cutter (using the handle of the compound) prior to hitting reverse. I'm off to have another go, fingers crossed. Thanks again Dave

Hi there, good to see that you now pretty much have the hang of it.

The bit I have highlighted in red that you experienced shows just what backlash is and how it can upset your day. As you reversed the machine you would have noticed that the screwcutting tool was no longer lined up with the thread properly but of course as you know it all comes good when going in the normal direction again.

Same thing with the top slide, if you feel you have gone a bit to deep (smaller diameter) on a part you just can't back it off a fraction you have to back a little bit more then go back in to the desired size. That's the backlash in the system again.

Hopefully I am making sense.

I just love it when people just like yourself are learning and stuff things up and then work it out. I feel a great sense of satisfaction for you as I did in my apprenticeship days when I did the same sort of stuff.

Cheers M