[Oldmanandhistoy]

Your stepper experiments sound interesting. Were you using a 3Nm Nema 23 motor for these? As I mentioned earlier, I have got 2.2Nm motors lined up for my machine, so hopefully they should do the job well. I know others have used the same motors as mine on the X3 with good results.

The stepper I have set up on the X is indeed a 3Nm Nema 23. I bought the 3Nm knowing it would be more than I wanted but as with all the stepper’s and drives I have bought to date I go over powered. It’s nice to have the extra power if needed and it also puts less stress on the electrics (I do the same with PSU parts also).

Do you know the weight difference between an X3 and a XJ20 table; it looks like the XJ table could be heavier than an X3?

I am wondering about the z-axis. Do you think a Nema 34 would be better than the Nema 23? I was going to use a belt reduction with the Nema 23, but I am having doubts. Maybe I'll leave the z-axis until someone else has done theirs .

If I use a Nema 23 stepper I will very likely use a 2:1 reduction but need to look into this further and do some calculations. If I end up using the Nema 34 (4.1Nm or 580 oz in) I would go direct drive unless I needed more power.

I had a day off from scraping today (my elbow and hands needed a rest). I've been at it almost full time since Sunday. The saddle was relatively straighforward to do, the table a little more tedious. One of the slides on my table was sloping across its width by about 0.1mm. This meant I had to scrape about 0.1mm off the other slide (the entire surface...) in order to get them both flat and on the same plane. 0.1mm doesn't seem like much, but it took AGES to scrape it off. I haven't done the base of the machine yet, or the z-axis. I am also going to have to replace at least the x-axis gib strip, because it has just run out of adjustment. Oh well.

I don’t envy the 0.1mm you had to scrape that a lot of scraping. I looked at adding a shim to the back of the gib strip but it brought the gib strip to far away from the adjusting screw so was a no go. I also considered boring out the holes and increasing the screw size but decided a new gib strip was the way to go.

I need to start looking at how I'm going to go about mounting the motors and ballscrews, but only after I've finished the scraping...it sure takes some patience.

I don’t as yet foresee any problems doing the conversion I have most of it worked out in my head. The X will be as in the picture with but a more substantial motor mount. I think I will very likely mount the Y axis motor to the base and use belt drive 1:1 but this may change when I come to it and the Z like already mentioned.

John

EDIT: I forgot to mention I have had the table doing rapids of 2100mm/min but this is only with the vice mounted. I should have added a few Kg’s to give a more realistic test situation.

[Oldmanandhistoy]

Can i get away with using the standard lead screws? backlash compensate in software?
can i use the rack and pinion and still CNC? though i do hope to upgade to lead/ball screw soon as i can.

Sorry for the bitty first post.

Luke

If your intention is to use the machine to drill holes then using the standard screws will not be a problem imho. Do the nuts have backlash reduction built in as the XJ20 has? If not you could very likely slit the nut and add some screws to adjust out most of the backlash or as you mentioned use software compensation.

As for using the rack and pinion on your Z; I originally bought an X2 which has R&P on the Z and gave this idea some thought. Unless you can find/come up with a good method of reducing the backlash you may be able to get away with it for drilling but again imho would be a none starter for milling. If there is a lot of backlash in the rack it may be possible to shim behind it as this will help. I personally think CNC’ing the rack would be far too problematic and would go straight to a screw.

Nema 32 motors are very large for a small mill you may get bad problems with rotor inertia.

The picture I posted will not be how I will do things when it comes to CNC’ing my mill proper as mentioned I have done it temporally to use as a power feed. If I wanted to do a quick job to use my mill for drilling only as you mentioned then I would say it is defiantly sturdy enough. The two motor stand offs are 12mm steel bar.

I hope there is something in that to help,

John

[Skullface]

Nema 32 motors are very large for a small mill you may get bad problems with rotor inertia.

John

That is frustrating. I spoke to both ebay sellers of these mills, and to Motion Control and Routout, everybody thought nema 23 would be pushing it a bit really, and to be safe, 34 was the only way to go. Surely the intertia issues are partly countered by the incresed Nm ability of the motors. ie more balls to stop themselves also.


RE: Z axis screw conversion, i saw an interesting X2 conv, that had the leadscrew sticking vertically off the top of the head, so its forces acted centrally, anyone seen this, has any idea how to go about it?

hmm, i feel abuse of anothers post, and might start my own when i consilidate my thoughts. still, all relevant to that same series of mills.

thanks for your time.

[Oldmanandhistoy]

That is frustrating. I spoke to both ebay sellers of these mills, and to Motion Control and Routout, everybody thought nema 23 would be pushing it a bit really, and to be safe, 34 was the only way to go. Surely the intertia issues are partly countered by the incresed Nm ability of the motors. ie more balls to stop themselves also.


RE: Z axis screw conversion, i saw an interesting X2 conv, that had the leadscrew sticking vertically off the top of the head, so its forces acted centrally, anyone seen this, has any idea how to go about it?

hmm, i feel abuse of anothers post, and might start my own when i consilidate my thoughts. still, all relevant to that same series of mills.

thanks for your time.

I’m no expert but its something to do with the motor over shooting its position and then bouncing back. If you take a look at some of the threads here on X2 (similar size to your mill I do believe) conversions you will find a lot of people using Nema 23 @ 1.8Nm with good results.

Hoss has a thread here about an X2 conversion with plans; it is probable you could adapt them for your own needs.

John

[jon_m3]

well make sure you both take lots of pics for me to look at and she how things work, this scraping sounds interesting i cant wait to learn how todo that.............


not

[itsme]

Hi,

Scraping sure is fun. I'm going to be moving on to the base of the machine tomorrow and then the z-axis. I stripped the rest of my machine down today and took a few quick measurements of the z-axis slides. I need to do more accurate and comprehensive measurements, but what I did do indicated that the end of one of the slides is >0.2mm higher than the middle (lengthwise) of the slide. This would explain why the head was so sloppy in the middle of its travel, yet almost impossible to move at the ends. I'm hardly looking forward to scraping the column after seeing these measurements, but it'll be worth it in the end (I've got to keep telling myself that... ).

Warren

[Oldmanandhistoy]

(I've got to keep telling myself that... ).

That really made me smile ; but it is absolutely true. When people ask you how did you manage to get that feed rate you can tell them “blood sweat and tears” lol. A week after finishing all your scraping it will be nothing but a distant memory but you will smile like this and dance like this :wee: when you get smooth accurate cuts.

Let me know when you are finished and I will tell you about a cheat method I use that makes the job half as long. Only joking no other way than the hard way unless you have a power scraper which I don’t.:violin:

John

[jollydog]

Hi
Just got a mashine like the one your asking about
the certificate from China is here
the weight is 135 kg of heavy castiron

[Oldmanandhistoy]

Hi
Just got a mashine like the one your asking about
the certificate from China is here
the weight is 135 kg of heavy castiron

Hi Jollydog and welcome to the Zone,

Thanks for posting that; I got one but never got to see it or the instruction manual that came with my machine. Both where in a small pile with a news paper and some other junk mail ready for me to look over when I had more time. Unfortunately due to my other half’s eagerness to keep my so called junk under control it ended up in the bin before I had chance to file it away. Lol

John

[jollydog]

Do you need a copy of the instruction manual ?

[Oldmanandhistoy]

Do you need a copy of the instruction manual ?

If it were a simple case of downloading it I would be grateful for a link but I would not ask you to go to the trouble of copying it for me. So far I have not needed it and don’t envisage I will but would have been nice to give it a read through.

Thanks for the enquiry though,

John

[itsme]

Hi,

John, I seem to have lost my instruction manual and inspection sheet, but I did have a chance to read through them both. From what I remember, you are not missing out on much...

I fully disassembed the z-axis today and was mildly disappointed by the column on the mill. Maybe I'm being a bit harsh on what is a hobby machine, but the column just doesn't seem to have the same robustness behind it that the table and base do.

I also managed to squeeze a 27 litre coolant tank and pump into the bottom of my stand today (it's a Chester stand and Sieg coolant system). The coolant system just wouldn't fit, but after I attacked it with an angle grinder and removed the legs, a handle and modified the other handle, it now fits in very snugly . I also touched up all the paint. This stand is going to work out nicely now. The coolant is on the bottom shelf and all the electronics will fit on the top shelf.

Have you made any more progress on your machine, or are you just running it manually for now?

Warren

[Oldmanandhistoy]

Hi,

John, I seem to have lost my instruction manual and inspection sheet, but I did have a chance to read through them both. From what I remember, you are not missing out on much...

I fully disassembed the z-axis today and was mildly disappointed by the column on the mill. Maybe I'm being a bit harsh on what is a hobby machine, but the column just doesn't seem to have the same robustness behind it that the table and base do.

I also managed to squeeze a 27 litre coolant tank and pump into the bottom of my stand today (it's a Chester stand and Sieg coolant system). The coolant system just wouldn't fit, but after I attacked it with an angle grinder and removed the legs, a handle and modified the other handle, it now fits in very snugly . I also touched up all the paint. This stand is going to work out nicely now. The coolant is on the bottom shelf and all the electronics will fit on the top shelf.

Have you made any more progress on your machine, or are you just running it manually for now?

Warren

Evening Warren,

Sounds good to me Warren.

Other than what I have done to my X axis (power feed) the only thing I have done is make a drawer style enclosure to fit above my coolant tank and wired up for 3 axis (another one to follow) it seems great minds think alike.

As for the column and spindle, I have as yet not touched it but plan to this week.

I think being very new to all this metal milling stuff it would be a good idea to run the machine in manual mode until I get the feel of things. Also while I am researching necessary components for the CNC’ing I might as well. Do you think it is the best way for me to go or should I just jump straight into CNC machining?

John

[Oldmanandhistoy]

Another slightly shocking discovery for me, was when I found plastic (or some kind of blue non-metallic material) gears for the spindle. Curiously, this is not what the Chester salesman told me...

A quick post for Warren,

I’ve just got to the point of actually seeing my gears, I hope the picture shows that they are in fact all metal. So it is very likely this would have been the information your sales person had. I have no idea why yours are plastic (or similar material) I can only imagine that my machine has had some spec upgrades. Obviously for me this is a happy revelation.

John

[itsme]

Hello,

John, the only positive thing that I can draw out of your last post is that when it comes time to replace my gears, I'll be able to get metal ones off the shelf (I hope) . Oh, and just to clarify my gear situation, not all of my gears are plastic. The two that you can see clearly in your photo are also metal on mine, but the ones that they mesh with (not so clear in your photo) are the plastic ones.

I found another interesting feature on my machine too! The part of the head that has the slides for the z-axis had a small casting defect on the surface of it. While investigating this, I decided to poke it with a scribe and the end of the scribe disappeared into the casting (I'm not sure whether I should be shocked by this or not). From what I can see, this defect is not too large and doesn't seem to be in a critical position, so I am going to work around it for now. Considering I paid the original Chester price for this machine (£900), I'm not overly impressed by all these non-standard 'features' that my machine has.

Oh well...

Warren

[Oldmanandhistoy]

Warren,

I would send the seller of my mill http://www.amadeal.co.uk/xj20.htm an email and see what he can do. IMO he is a first class seller and I would think he would go out of his way to get you the parts you needed. The trouble will be if indeed they are an “off the shelf” parts that shelf will be in China more than likely so if they go all of a sudden it could take weeks to import them. The picture I took wasn’t very clear but the defiantly are all metal. It would be interesting to know if your seller had that machine in stock for a long time and after that machine had been imported they made some improvements. To the best of my knowledge Amedeal have a fast turn around so it is very likely my machine was only 2-3 months old when I got it.
As for the void in your casting I could not say how common that would be but I do know there are none in mine. The only defect I have found in my castings is a small cold spot on one of the base ways which I needed to stone below the surface so as not to affect things long term.

If anybody is following this thread and would like to see more pictures of the machines parts please let me know as I have a few more now in my camera.

John

[itsme]

Hi John,

That's not a bad idea - I might send an email off and see what he has to say about parts.

On another note, I haven't touched my scraping in nearly a week, but there is a good reason for that (and I just can't help but brag about this one )! You'll see in the photo that I managed to find a very nice, old, Brown and Sharpe camelbacked straight edge (36" long), so I've been waiting for it to arrive in the post, which it did this morning! I'm quite impressed by the condition, considering it must be pretty old. In fact, when I opened the box, it had that distinct 'museum' smell about it - nothing quite like the smell of old iron .

It's back to the scraping for me with renewed enthusiasm!

Warren

[Oldmanandhistoy]

It's back to the scraping for me with renewed enthusiasm.

Very nice find Warren,

When I look at the scraped face on mine it makes me feel very humble. If everything were made to this quality our rubbish tips would be rather empty. Unlike the vast quantity of Chinese (and other) discarded short life products we buy today. It will make that long Z axis a piece of cake and you’ll be finished by lunch time lol. I’ve just started scraping my Z axis saddle and am quit determined to have all my ways finished this weekend.

Pictures are my saddle before scraping and after its first blue; you will need to look closely for the blue. Even though it does not look good the error is very small and would very likely be fine for most as is but I am very fussy.

John

[S_J_H]

Scraping is something I need to learn. How do you go about scraping in the angled dovetail surface and keep it square to the flat surface?

Steve

[Oldmanandhistoy]

Scraping is something I need to learn. How do you go about scraping in the angled dovetail surface and keep it square to the flat surface?

Steve

Hi Steve,

Scraping the dovetail is very likely beyond my talents so I will lap all of mine and just scrape in some oil reservoirs. Doing lapping correctly is a very difficult task to put in writing (for me any way). I have searched the web and can not find anything that describes it. If you know of a link I would be grateful as I have a feeling Warren is going to ask me for an explanation as soon as he has finished his scraping lol.

If you want to scrape them you will need what is shown in the third last picture in this post http://www.cnczone.com/forums/showpo...5&postcount=26 and do them as you would a way surface. I don’t know if you have read the thread the post came from but if not I think you will find it very interesting.

Hope this helps

Picture is my Z axis saddle half finished if anyone is interested; well one side of it anyway.

John