Changing mains plug

The SIEG C4 lathe that I bought from Axminster Tool Centre works on 230 VAC 50 Hz mains voltage, the same we have here in Finland. The only problem was that the power plug in the end of the cord was some British type and not the kind of we use. So I went to the local hardware store and bought a plug that is made of rubber, rated for 16A and has an insulation class IP44. The cost of the plug was 1.79 EUR, so it is cheap.

I don't know of other countries laws on electrical work, but here everybody has the right to change a power cord to a device. Technically I'm not changing the cord but in reality I'm doing the very same end result with the same connections so it doesn't count.

First thing to do was to cut the original British plug and toss it. At the same time I stripped the insulation down about 40 mm and clipped the neutral and live wire about 5-10 mm shorter than the grounding wire. This is made so that if you yank the cord and the wires get ripped off, the ground connection is the last one to rip off and in some cases it can save your life. In this plug it doesn't matter that much, but I have a habit of doing this always so I don't forget it.

I stripped the insulation off of the ends of the leads for about 5 mm and twisted the stranded wire together. Using a screwdriver I opened the new plug and screwed off the strain relief.



First I opened the screw for the grounding wire (green-yellow) and put it under the screw and tightened. After that I bent the live (brown) and neutral (blue) to their attachment points and screwed them tightly. This plug type is non-polarised, so it doesn't matter which way you attach the live and neutral. Last I screwed the strain relief tightly so it clamps on the black insulation of the cord.

Pulled the cover on and screwed it snug and this modification is done.

How to change gears in C4 lathe

I have to admit that this new change gear system SIEG has done is just wonderful, as the change can be done in a minute and easily without any modifications nor hard to reach places.

First open the small socket head cap screw from the front to get the gear cover open. Inside you'll find the regular arrangement of gears. In this picture I have the new gears ready and the BC-gear pairs mounting axle dismounted and all the necessary tools to make the change.


Put the sleeve with the key on the axle, then the small washer and thread the T-nut on the axle a little. Slide the T-nut behind the geartrain holding arm and the washer on the front side. Snug up the axle with fingers.


Slide the B gear on the sleeve and then the C gear after it. Now move the axle so that the C/D pair engages properly and tighten the axle with a 7 mm wrench. If the A/B pair gets in the way or is not engaging, open up the socket head cap screw in the lower end of the arm, located just behind the D gear and turn the arm down a little. When you have C/D engagement correct, move the arm to engage A/B properly and tighten the arms screw.

As a last operation drop the cutout washer on the axle and thread the locking nut in place. Even fingertight is enough, but I'll usually snug it up a little bit with a wrench to be sure it doesn't open up under vibration.

This is so easy and fast to do than on the older C2 lathe that I could change the gears just for the fun of it! :)

Bigger tools to the C4 lathe tool post

The original tool post that comes with the SIEG C4 lathe accepts up to 13.8 mm thick tool shanks, but the maximum tool height to axis of rotation is only 10 mm. I think this a place where SIEG should make a change to their lathe as the lathe has enough power to use bigger tools. Only needed operation would be to make the tool post 2 mm lower.

My own way of modifying the tool post was to use a surface grinder to take off 2,00 mm from the bottom of the tool post. Because the tool post goes over a small shouldered bolt in the compound rest, the bolts shoulder had to be turned shorter. I took about 1.6 mm off of the length of the shoulder in a lathe and chamfered the edge.

I bought a DNMG insert holder from eBay that had a 20 x 20 mm shank and wanted to use it in my lathe, so again had to modify it to fit my tool post. I tried my best to search for 12 x 12 mm shank DNMG insert holders, but could not find any, so the 20 x 20 mm shank had to be bought. At the same time I also bought a 10 piece package of DNMG 110404 NF inserts. The nice thing with these inserts is that they are negative inserts, meaning the insert can be used four times and for me this means 1 EUR per insert edge, so very cheap.

To minimize measuring and setups I used a surface grinder to knock off all the material needed from the insert holder. First I measured that I could take about 5 mm from the bottom safely without messing with the insert retaining screw. Then the remaining 3 mm from the bottom I took so that I created an edge to the holders bottom as can be seen from the photos.

Last operation was to take 8 mm from the backside of the holder so it wouldn't hang so much out from the tool post. This was easy and fast and the last operation I did was to chamfer all the sharp edges with a file. The shank material was hardened, but filed quite okay.

Last thing to do was of course test this new tool with the new tool post mod. The tool sat very well, about 0.1-0.2 mm under the center of rotation as I checked it with a dead center mounted in the tailstock. By the way, it is a good practice to keep something in the tailstock taper as it prevents chips from entering it.

For the test I used RPM of 600 for a 60 mm diameter scrap piece. This gave me a surface speed of 113 m/min now that I calculated it. I usually aim for about 120 m/min minimum if the steel is nothing special. The feed was 0.15 mm per revolution. Depth of cut was 1 mm and the lathe happily purred away throwing short painfully hot deep blue chips. The finish was very good, considering a feed 0.15 and an insert radius of 0.4 mm.

I'm very happy of this tool post modification as it means that I can finally use the lathe :) I'm still going to buy a quick change tool post, but this will do until then.

Test chips with the C4 lathe

Two words: Eye protection. Really, this thing makes chips fast and not just bogging sounds like the old C2 lathe I had. Here is a nice comparison photo of the old C2 lathe that I had and the new C4 lathe that I now have, both mounted on the same table in both pictures. Have to find a place or build a stand for the drill press, as it is a good thing to have when the mill is reserved.



I whipped up a quick test to see how much better this new C4 lathe is compared to the C2 that I previously owned. I found a piece of steel scrap from my material box that measured about 60 mm in diameter. The only tool that I had ready for this test was an old but sharp HSS turning tool measuring 7.5 x 7.5 mm, so I had to shim it up 2.5 mm to get to about center height.

I used an RPM of 150 which means about 28 m/min surface speed. The recommended speed for HSS in steel is about 25-30 and with coolant, but I did this test dry. I touched the workpiece and dialed a depth of cut of 1 mm and engaged longitudal feed. The feed was 0.15 mm per revolution, so something between a roughing and finishing cut.

As the tool came to contact with the steel bar I could hear a small bogging sound in the RPM but at the same instance the motor grunted more power and chips started to fly around. Hot blue chips on to the table, the floor, over me and that was the point I withdrew the cross slide and cut off the feed. Just..wow! On the old C2 lathe steel would have been a problem and basically anything with a 60 mm diameter, but this machine barely noticed that there was something in the way of the cutting tool.

The other test I conducted was a drilling test to see how big drill bit can be used safely in to solid steel workpiece. The tailstock has a #2 Morse taper and biggest drill I know for that size is 24 mm in diameter, so I used that size drill bit. The tailstock ram is better than in the old C2 lathe as it can hold a Morse taper with the tang in place. But there is no slot in the end of the ram for the tang to go in to, so there is a risk that a little bit loose tool can turn in the taper.

I set the RPM to 350 to provide about 28 m/min cutting speed and I had no pilot hole in the test piece. The tailstock tended to come loose from the lever lock but when I kept it in place the drill went in nicely and the machine power was more than adequate to drill the hole.

After drilling I noticed that the tailstock ram was a little bit stiff and revealed that the small M6 grub screw that acted as a "key" was a little bit bent. No wonder under that load, but have to put a new screw in there.

I can't wait to get my new Multifix Aa type quick change tool post and to modify the DNMG carbide insert holder to a 12 x 12 mm size, as it originally is 20 x 20 mm. I already milled and surface ground the height to about 11.90 mm, but the width is still to be done. The turning insert holder cost me 68 EUR plus 36 EUR for 10 pieces of DNMG 110404 inserts. This holder I bought from the German eBay seller cd-tools.

Frank J. Hoose Jr. at mini-lathe.com did also a nice review of this C4 lathe which you might find interesting.

Pros & cons of the SIEG C4 lathe

I have had the SIEG C4 lathe for a couple of weeks now and although I haven't had the opportunity to turn anything to chips with it yet, I have seen quite many good and not so good things in it while disassembling, cleaning and assembling. My comparison level is basically the older C2 lathe and the "real" lathes that I use at work (TOS and one huge chinese machine).

Pros

• Weight is a nice 94 kg and comes from the bed casting mostly. This is a good thing to have, except I would list it as a con when I have to lift it to the workbench or move it around. The size of the lathe in terms of travels didn't increase that much from the SIEG C2 lathe, but the weight really jumped from the 37 kg mark, so this really is a big jump from SIEG.
  
• The 1000 W brushless motor really provides tremendous torque versus the C2 lathes 250 W DC motor that had brushes.
• LCD dislay for RPM reading
  
• Leadscrew cover keeps the chips out of the screw and also protects fingers, as the screw has a keylot along its lenghth and it has quite sharp edges.
• Leadscrew bearing blocks and the apron both have hardened pins to lock them in certain place and this helps keeping things in proper alignment. More points from using pins that have a threaded hole to help yanking them out if needed.
• Tailstock has a lever operated locking mechanism, very fast to use especially when drilling deeper holes than the quill movement is.
• All metal change gears are nice and have precise holes that allow smooth sliding fit to the axle ends when installing, unlike the C2 plastic gears that had an undersized hole in them.
• Metal gears in the headstock transfer more power than plastic ones and will also handle more loading conditions without chipping a tooth.
  
• Oiling ports everywhere: Apron, carriage, tailstock, spindle, gearbox axles, leadscrew bearings, cross slide, headstock etc.
• Split nuts in the compound and cross slide movements provide a mean to adjust the backlash to a minimum. In basic turning operations the backlash doesn't have any effect on anything and in some instances it is a nice feature to have.
• Carriage handwheel has a graduated collar that measures 0.5 mm between lines. Very good update from the C2 that had no kind of way to get Z-axis measurements.
• Carriage handwheel can be disengaged by pulling so that it won't rotate while power feeding.
  
• Cross feed helps hands if turning larger diameter parts.
• Feeding directions are logical in the sense that when the Z-axis feed is towards the headstock, the cross feed is towards the center of the part.
• The changing of gears is easy due to the B/C gear arm that is very quick and easy to adjust.
  
• Total indicated runout of the spindle MT3 bore is 0.005 mm or less
• Total indicated runout of the chuck index is 0.005 mm or less
• Total indicated runout of the spindle face is 0.01 mm or less
• The tailstock ram accepts full size #2 Morse taper tools unlike the C2 lathe that required the tang to be cut off to utilize the full movement of the ram.
  

Cons

• Spindle and leadscrew relative rotation directions are fixed. There is no change lever like the C2 had, but then again, how many times that was needed? Personally I never used it.
• Cross feed speed is sssslooowww compared to the longitudal feed at the same change gear setting. Basically if the longitudal feed is 0.1 mm per revolution, the cross feed is only about 0.032 mm.
• The change gear cover box doesn't come off unless the electrical cabinets panel with the small fan is removed first, as the panel screw heads will be in the way. And removing the little screws is dificult because the gearbox cover is in the way.
  
• There was either sand mixed with heavy oil/lube or some sort of course lapping compound in the headstock gears that was causing huge noise and was a possible wear inducer.
• Almost every electrical wire is either blue or black inside the machine. Not good when trying to figure out where some wire went, but at least some wires had labels on them.
• The beeper is plain annoying. Beep when you turn the machine on, beep when you push the buttons. A jumper on the PCB for disabling it would have been a nice feature.
• The safety interlock in the chuck guard is not logically done: If you don't push the microswitch (like remove the whole shield), the machine runs fine. But when you push the switch, the machine shuts off.
• The tailstock can bump in to the gib screws of the cross slide. This could be prevented by installing a small screw in front of the tailstock.
• Painting has been done for a half-assembled machine, as there is painted socket head cap screws, some not painted, some parts painted that should not be (like the carriage gib "paws") and the paint also flakes off easily from the cast iron surfaces.
• Carriage gibs don't have counteracting screws or locking nuts for good adjustment.
• The cross feed dial is reading radius and not diameter as would be useful.
• The cross feed dial numbers don't correlate to any "real" values, they are just for counting.
  

All things considered with the relatively low price of 1100 EUR that I paid for this is a very good investment and the SIEG quality has gone up since the C2 lathe. Personally I can suggest this C4 lathe to others and say that I very much like it.

Cleaning of SIEG C4 lathe

As the lathe was covered heavily with protective red grease, my first task was to clean it all off and lubricate the machine properly. As I was cleaning the lathe, I notice that the bed number was 00425, meaning that this is a very new model and I got one of the "first ones". Just for comparison, the previous SIEG C2 lathe I had was with a number of 22xxx.


For cleaning I used paper towels and lots of turpentine that I spread with a small paint brush after getting most of the smears of grease away with the towel and finished with a turpentine soaked towel. The bed way was quite easy as well as the slides and took me about 30-45 minutes.


As I removed the chuck to clean the spindle end, I rotated the spindle to get to the bolts and heard small grinding sounds. Thought first that the spindle bearings are already broken, but when I disengaged the spindle from the auxiliary axel the sound stopped. This required a peek in to the headstock, so I unscrewed the cover on the casting and noticed grease on the gears.

Nope, it was not grease. Metal gears covered in thick greasy like substance that felt more like a coarse lapping compound. I don't know if they have lapped the gears in place for quieter operation and in a rush didn't bother to clean it up or is their grease gun full of small grinding particles and chips.


As I didn't want to disassemble the headstock at this time, I tried soaking the gears in engine oil and rotating them. The oil was mainly picking up individual partcles, so I tried with turpentine and found out that it flushed the grease quite nicely, but didn't get everything. I ended up using both, first soaking with turpentine and then with oil and couple of times wiping with a paper towel between the teeth of the top most gear. About five minutes later I had a nicely working and soundless headstock gear pair.

All the accessories went through the same turpentine treatment. The change gears had thick red grease on them, mixed with dust or something similar. The paint brush and a pail of turpentine got rid of everything easily. A nice feature of these all metal gears is that the hole in the center is a free siliding fit to the respective axel as opposed to the C2 lathes plastic gears, that had a hard friction fit which was a PITA.

I removed the lead screw cover to examine the lead screw closer. The lead screw was covered with the red grease and a closer look revealed that there is only grease on it, so for now I left it alone. However, I was intrigued to take a peek of the pillow blocks that hold the screw to see if there is anything better than the C2 lathes cast iron blocks. The tailstock end seemed to have a bronze or brass bushing where the screw rotates and the block itself was pinned and bolted. These hardened pins are an indication for me of precision, as they lock the block in certain place and position.

In the headstock end of the leadscrew I had to remove the plastic electrical box to see the screw. The electric wires were protected from the screw with a small floded steel sheet and under that was a very positive surprise: A flexible connector and a thrust bearing! Seems that SIEG really has thought about these things and this really is showing up as a quality product so far.

The carriage also had some interesting features. In the photograph to the right I circled some items from the top view. Yellow ones are threaded holes that have a grub screw to protect it from swarf and these are for some sort of attachments/accessories. The blue ones are for adjusting the front side gibs that hold the carriage down. The green ones are yet again hardened pins to align the apron to the lead screw. The red one is for locking down the carriage to the ways when for example parting off or taking a truing cut with the cross feed.

I removed the carriage front side gibs or "paws" to clean them up. They had the same red grease all over and some paint chips on them. I'm just a little bit confused as to how I should adjust these, as the lathe manual is of no help at all and these are different than in the C2. There is no obvious adjustment screws that would counteract each others, there is only those two small socket head cap screws that hold it in place. I just snugged them up a little bit so the carriage won't lift, but in the end the cutting forces are pushing the carriage down to the prism way, so I think these paws are just to keep it from lifting up easily. If someone knows better, write about it in a comment to this article.

Behind the right hand side paw there is a locking element that locks the carriage to the ways. I did not have a magnet at hand so I didn't remove it, but once I find one, I'll check it also. I'm suspecting that it is just a little bit of L-shaped and the only screw just lifts it up to lock the carriage from movement.


To get best access to the electronics compartment located in the back of the lathe, I had to get the gear cover off. This means removing every gear and the drive belt. While removing parts I cleaned them all and noticed a nice desing feature on the gear axles: They have an oiling port in the visible end and a small hole goes halfway through the axle and then there is a cross drilling. This provides oil to between the axle and gears to lubricate them properly. Very clever idea!

The gear covers frame however had one error: It will not come off if you don't first remove the four small screws on the backside of the electrical box that is located inside this gear compartment. I think I'll just take a Dremel or a round file and make some sort of small cutout to the frame where the screws are located so it slides in and out without unscrewing those small screws. Otherwise the end shows the usual SIEG style of finishing with a paint on parts half assembled, as indicated by the paint spots.



The controller board, as seen in the above photos, is located in the large box behind the lathe. There is a hefty finned heat sink that provides cooling together with a small fan to full wave bridge rectifier and six huge (probably) MOSFETs. The capacitors are so big that there is a cutout in the heat sink for them. The board itself has nothing special except very good connectors. There is a small additional daughterboard connected with a couple of rows of pins and this contains an ATMEL microprocessor. Didn't look that closely but I suspect that it is responsible for operating the display and keypad.

As I put everything back, I ran into a problem: How to get those small wires through the white plastic tube that goes through the headstock and is already full of wires? Well, found a length of copper wire, pushed it through and made a small loop and to this loop I attached the wires and pulled them through.

SIEG C4 lathe arrived

My new lathe arrived on Monday, 13.12.2010, brought by a TNT courier. Incredibly fast service and delivery from Axminster Tool Centre in UK, as I ordered the lathe 03.12.2010 and they did not have it in their warehouse at the moment. This was my first purchase from Axminster and I was very happy with their customer service, so I can easily recommend them as a good source of tools for quite cheap.

The freight from UK to Finland cost me about 140 EUR, so not bad for a 130 kg shipment that measures over 1000 x 700 x 500 mm in size. I already blogged about this lathes specs previously, so I won't go in to details in this post. As I knew the package dimensions I checked my doors and elevator that the package fill fit through them all and with the weight in mind I bought a hand truck capable of lifting 200 kg for a price of 39.90 EUR (from Biltema).

I think it was about 27.4 seconds after I got the package inside and the doors closed when this happened. As usual, the safety inspector already did some jumping tests on the crate and tried to tip it over.



Using pliers I ripped the steel bands off of the crate and with a regular hammer I pried the top open. The lathe looked as expected and nothing obvious was missing or damaged. The usual aroma of fresh new machinery and a lingering smell of grease filled my nose as I pulled the plastic cover away. Most of the space in the crate is occupied by the chip shield that is located behind the lathe. It weighs quite much and makes moving the lathe more difficult, so I unscrewed the four socket head cap screws that were holding it.

All the accessories and tool were inside a small wooden box. This includes the change gears for threading and/or feed, the chuck key and a small wrench for tightening the screws in the tool post. The gears are all metal which is nice, compared to the plastic gears in the SIEG C2 lathe. And these gears include a 127 tooth gear that enables the lathe to thread imperial threads without approximation.


Removing the sides of the crate was a small task, as someone had went haywire with a stapler. But there's nothing a big hammer can't fix ;) Opening the crate revealed the lathe in all its might and it really looks like a slick machine. I even like the color, don't know why. In this photo I was looking for the bolts that secure the lathe to the crates bottom and also was looking for some good lifting points. While searching I also discovered myself looking at my cat :D She sneaked up to sniff and snoop around and was very curious...I think too curious, might have to keep on eye on her...

This is the lathe in the setup I used to lift it off from the pallet to the floor. I removed the tailstock and wound the carriage all the way to the headstock end of the bed. Then I grabbed under the headstock, left hand under the motor and right hand under the small ledge and lifted it with a straight back so that the tailstock end of the bed was resting on the pallet. My helping hand removed the pallet and I could then lower the headstock on the floor and lift the tailstock end down also.

Next I removed the plastic chuck guard and the small metal lid that covers the spindle opening in the gear trains cover. I parked my hand truck behind the headstock and lifted the lathe to stand on the hand truck. The gear train cover is metal and it will easily handle this load if not shock loaded.



While the lathe was like this, I could take measurements from the mounting holes easily and accurately. I discovered that the holes are spaced 110 mm apart and there is 590 mm from the tailstock holes to the middle holes and then another 90 mm to the headstock holes. And curious as I was, I HAD to unscrew the bottom plate of the apron off to see what is inside. This lathe has power feed for carriage and cross slide and these small gears provide that. The drive comes from a worm screw that is rotated by the lead screw. This turns the bronze gear which in turn turns the small, movable gear. This small gear can be moved to engage with the apron front-most gear for cross feed and the gear near the bed for carriage feed. If you engage the power feed, the threading half nut is locked from moving to prevent an accident.



The cross slide and compound both have a thread pitch of 1 mm and adjustable bronze nuts. The only bad thing is that the carriage dial is measuring the radius. Would be nice from SIEG to see diameter reading cross slide dial, makes working easier. Oh well, have to make a modifications for this :) The best thing of these is that they slide so smooth compared to the C2 and this is because there is a bearing in those handles.

And WOW! 1000 W brushless DC motor, delivering awesome torque even in low speed (100 RPM). This thing is just huge and looks very good. This is connected to the spindle driving mechanism via a toothed belt. And yes, that is my dirty hand (try polishing molds for 8 hours and it will get that way).


After I had drooled enough, I grabbed the hand truck and rolled the lathe to my "shop". Really it is just a 13 m² room that doubles as a storage as you can see. The bench I made for C2 lathe is just behind me and is to be tested with me and heavy weights that it will hold without squeaks under the C4 mass.



Now I need a few hours of time, a small container, brush, rags and kerosene or some other solvent to remove the packing grease. And maybe a beer or two along with this operation ;)

A new lathe in mind

Seems that I've been too busy to write updates in here, as I've been in work and tried to do a lot of lock related stuff in the past months. Sorry about that, I'll try to change that :)

Oh well, xmas is coming up and I have outgrown from my mini lathe a while ago already, so I've been searching for a new and bigger (mini) lathe for my workshop. Around the time I got my mini mill, SIEG Industries updated their lathes and mills to have a brushless motor instead of the brushed DC motors like in my C2 mini lathe and X2 mini mill. Now it seems they have many of their products offered with this new motor design and that makes everyone happy, as the new motor type offers a lot of torque in the low RPM range and is more silent than the previous type.

As I have loved the C2 from SIEG, the obvious choice is to look from SIEG again. I pondered this for quite a while already and decided on the new C4 lathe that has the updated motor version and fulfills my needs more than enough. My list of functions was more torque, more power, more versatile cross slide and bigger swing.

Comparison of specifications for C2 vs. C4



A search for a distributor lead me to Axminster Tool Centre website. Their offer is very good and tempting and I have heard all kinds of good from them. I got a quote for the shipment to Finland and it is a little under 150 EUR, which to me seems cheap. The total for the lathe and shipment would be about 1250 EUR (VAT included), so I'm only missing about 1000 EUR from the price.

I already ordered a Multifix 40 position quick change tool post from ebay.de with 5 holders for the price of 290 EUR plus 20 EUR shipping. A very good and rigid tool post that I have used at my friends workshop and in school we had one and I love it that you can position the tool in so many positions without turning the holder itself.

I will make a new update when I get the lathe, in the mean time I'll post something else and also try to think of a way to lift the lathe on my workbench...