Thank you Justin. The OX is a great design and place to start learning and building a CNC machine. Gerald (Area51CNC) has shown a modified OX can cut aluminum as long as you take light cuts.

The standard OX has a few limitations which a few members have found good solutions. The X axis beams need to be bolted together or replaced with a larger beam. The belts need to be doubled to remove stretch or replaced with acme leadscrews or rack and pinion. I have chosen to go one step further and replace the extreme wheels with linear bearings.

It's all a fun and very enjoyable learning adventure. Be patient, save your money and absorb as much as you can before spending money on parts you will replace if you honestly think you will enjoy this hobby.

For example I have no regrets spending the extra on the Gecko drivers and stronger stepper motors... The belt drive was a little mistake for me, but it was also worth doing just to get a machine up and running quickly. In hindsight the acme leadscrews are a better solution and worth the effort. A relatively cheap and simple mod... See my other build thread http://www.openbuilds.com/threads/another-aluminium-ox-just-started.936/page-5

 

Thank you, progress has been very slow because of vertigo issue!

I changed the name of the build because the design has evolved a long way from my original OX modifications. Sadly it's not really an OX design anymore, I hope Mark has no objections to me sharing my build process! My Aluminum OX build started me on this adventure and can give Mark full credit for this... Lots of credit also goes to Gerald who has been very supportive!

I choose to post here because it's a good group of people who are always willing to help each other...

Below are a few pictures of the Bosch linear bearings, they are big, strong and very precise, machined from polished steel with endcaps. Wonderful German quality. The rails are 20mm square and precision ground. Awesome!!!

 

Thank you, Justin. The Bosch linear bearings were advertised in local company sell off, so the price was an awesome deal for this quality, but still far more I than first planned. I originally planned to buy the SBR16 from China on eBay. I bought one set and would still recommend them.

McMaster 1/2" 5 start acme lead screw, is currently an awesome price at $18 for a six foot length.
http://www.mcmaster.com/#99030a704/=wokojq
I bought anti backlash nuts from CNCRouterParts.
http://www.cncrouterparts.com/dumpstercnc-acme-assembly-p-36.html
Both are really good quality and highly recommended. I decided to use these for my original OX which I plan to sell when this machine is complete.

The 4" * 2" X axis extrusion can be bought from Misumi USA or 80/20 on ebay.

Iwuns build is really worth looking at. A nice balance between linear rail quality and price.
http://www.openbuilds.com/threads/linear-rail-to-combine-with-vslot-parts.1414/

http://www.igus.com/wpck/3596/drylin_w

Linear bearings can be really, really expensive, because many are built to high tolerances and designed for production environments. I must admit I suffered sticker shock when I received many quotes!

I going to ask Gerald to cut the gantry plates and use a local precision water jet and laser cutting company for the plate work. Local steel supplier for the tube. Welding I will do my self because this was my original trade.

For a hobby machine I would seriously consider the SBR16's from China or the Igus double rail setup.

I'm not in any big rush on this build, just buying the best I can afford one part at a time.

 

I agree Jeff, at that price for brand new, in original packaging I could not resist even though it was a lot of money! But no regrets, at $550 CDN

Bosch Roxoth typically sell for $35 US to $80 each and this is a good price. Rails are typically $10 per foot on eBay. Full retail is over $250 each!
http://www.ebay.com/itm/NEW-Rexroth...728?pt=LH_DefaultDomain_0&hash=item3387eeaf68

I found HiWin prices are typically higher. Prices can get really silly!

Sadly I'm still off work with vertigo, it's a real *****. Thank you for asking!
So no workshop progress very sadly.

 

Anyone looking for CNC machine inspiration made from heavy duty extrusion, linear rails, ballscrews should look at this thread on cnczone.com
Awesome craftsmanship and a workshop to dream about!
Here is just a little taster of his awesome machine.

More can be seen at this link.
http://www.cnczone.com/forums/diy-cnc-router-table-machines/182294-cnc-2.html

This thread gives some good suggestions for rail alignment.
http://www.cnczone.com/forums/cnc-wood-router-project-log/127895-cnc-forum-6.html#post1067507


This thread has great reference material for building a welded steel structure and how to use self-leveling epoxy to create perfectly flat the surfaces for the linear rails to mount onto.
http://www.cnczone.com/forums/cnc-wood-router-project-log/134962-cnc-machinist-engineering-4.html

 

Thank you Kyo, I did not know this! Thank you for the link to grabCad files. The files are in Rhino file format.
Agree 100% he builds awesome machines!

 

Antibacklash ball screws and bearings arrived today from China. The guy (Solar.Jean) was great to communicate with and did a very good package deal price. http://stores.ebay.com/enjoylife/

Excellent quality and very happy with them. Now waiting for the ball screw holders to arrive.

 

A sincere thank you for this link and your recommendation, this is a vertigo technique I have not tried. But after six weeks being off work, I'm willing to give anything a try, especially if it helped you!

I going to try the Gecko 540 first, if I need more powerful stepper motors I will buy another GeckoDrive solution. I don't enjoy tinkering with electronics, so I'm happy to pay the bit extra for a quality product with an excellent reputation.

I'm happy to share my experience and thank Gerald for all his advice & support...

 

WARNING, if you are curious like me... Don't try to take the ball nut off the lead screw to inspect the quality.

I was shocked, that all the ball bearings fall out! I blame the vertigo for a lack of clear thinking....

One & half hours, later after watching a youtube assembly video, all the balls are back in the 3 races inside the ball nut... For the curious, this is a Chinese ball nut, repacking video...


I now know how they work!!! But it's a lesson I do not recommend to others.

 

The G540 Is an all in one solution, all 4 drivers in one very compact unit. The only thing you need to add is a power supply, heat sink, emergency switch and limit switches. I bought 380oz complete kit from cncrouterparts. It's a little pricy, but very simple to setup with Mach 3 or Mach 4
http://www.cncrouterparts.com/4-axis-diy-nema-23-electronics-kit-p-75.html

I also wanted a solution that would work well with mach3 cam software, because every really experienced person said Mach3 was robust and well supported.

Neil who built "The Frog", has just switched and has experience using both... Neil appears to be very pleased with the enhancement...

Tweakie who is a very experienced CNC user also uses the G540...

I read too many posts with members having problems with other cheap solutions. Plus lots of experienced builders said great things about the Greko products.

 

Gray
I agree 100% that YouTube had the solution once again. It's great that people take the time video almost everything and share the knowledge...

 

I have been planning my steel cutting list now I have accurately measured and double checked the lead screws and bearings. Also look over the design one last time and reviewed a number of steel builds on CNC zone.

Many typical DIY CNC have the following weaknesses. Side gantry plates which are too thin, the X axis extrusion is too light and a base which is flexible.

I also looked at machines that use high-quality linear bearings always have only one bearing on each Y axis. After speaking with an engineer, he suggested that I did not need two linear bearings per side because the square linear bearings are extremely rigid.

The other advantage of positioning the bearings on top of the tubes is I get more cutting area without changing the length of the rails or leadscrew.

Hence another redesign...


I'm going to have some 1/4" flange plates laser cut and then tap them for bolting the end plates on.

Then I will weld these into the end of the 5" * 2" * 1/4" wall thickness Y rails.


I plan to have the end plates laser cut and will then bolt these into the Y beams. Then have the top sides machined to make sure they are straight and flat.



At this point, I plan to tack weld all the beams together to create a very strong overall structure.
Next I thought I could save money by using steel tube for the X gantry beam. 6" * 2" and again weld in flange plates on the ends of the tube
This results in the need for very low height aluminium gantry plates because the Y axis tubes are also tall.


Below shows the linear bearings attached to the X axis...

 

Thank you again for you suggestions and links Flo. I will read with great interest... Your suggestions are always welcome to make me rethink assumptions!

I served UK apprenticeship in fabrication and welding, so I fully understand stress and distortion involved with welding. Heat treating a welded beam structure, does remove the internal stress but it's not always successful in relaxing the structure in a way that is desirable! More than once I have seen a frame that was not bad before heat treatment come out as scrap, so this process has advantages and disadvantages.

I thought I would try the self leveling epoxy method the get the Y rails level. Tweakie how did you get your Y rails straight and true?

I honestly don't need super accurate or high speed production machine, but I do want a machine which is strong with minimum vibration. After reading endless threads, I came to the conclusion that aluminium is not the best choice for the axis beams. But is a great choice for ease of assembly and weight, but a poor choice because it flexes and is expensive.

Given I have welding expertise and equipment then it appears to be a good choice for me personally. I noticed when tapping holes in the OX extrusions how fragile aluminium is when tapping bolt holes, this makes it great for a novice, but not good for a heavy duty CNC machine.

To answer Joe's question. I took a two pieces of 2" * 3" aluminium extrusion and compared that with a single piece of 6" * 2" 1/8 wall steel tube. The steel tube is heavier but not by that much. My feeling was go with the steel tube because it's cheap, if I change my mind I can always switch to aluminium.

On the CNCZone forum many builders have built much larger and more robust CNC machines, so I'm not concerned about the weight. Also the general feeling was a little heavier X gantry helps reduce vibration when machining soft metals.

My reason for bolting on mild steel end plates to the base was it is easy to remove and replace if required then it's easy to experiment with motors and gearing.

I'm NOT an expert in building CNC machines, but enjoy sharing my thought process and design models.

 

SW3DP (Jack), you edited your thread you posted earlier today. I had to think more in terms how to answer your questions. Sorry for not replying straight away!

Building & designing a CNC machine does require a tremendous amount of reading and research. The hardest part is there are so many opinions and ways to design the machine. The positive aspect you get to meet lots of knowledgeable people by posting your ideas.

Flo for example was the person who suggested going to the better quality square rails. This made me search my local online selling service and found a great deal on excellent linear bearings. I was happy with the Chinese bearings, but these are so much better! The additional cost has slowed down the build process, but the final machine will be better.

Another information gem today was using a belt drive system to tie both Y axis lead screws together... I don't know if I want to go this route yet, but has started my brain thinking about this approach. Until today every single motor solution I found was seriously flawed in y opinion because they hand just a single motor mounted in the center with a single leadscrew . I much prefer the dual lead screw design... But Flo is also correct that missed motor steps could cause problems...

As I get quotes and prices I will edit the build log, so other builders know how much this style of CNC machine truly costs.

I have to agree the total cost of the build will be far more than I originally planned. But part of the pleasure is building, designing and experimenting.

 

Flo, its funny, I have been decreasing the Z clearance by reducing the height of the Y tubes, I honestly thought I was too high with 5 1/2" of clearance between the base & the bottom of the gantry. This machine will mainly be used for machining thin materials, with the odd 2" thick piece of G10.

But you are correct it's easy to build up from the base, if I ever want to build a vacuum table.

I have always liked the Y axis rails on the side to help prevent dust build up. But after reading lots, it's a lot easier to mount the rails on the top accurately because I'm trying to avoid the cost of having a machine shop milling the frame after welding. The second reason for placing them on the top is the X axis gantry sits on the Y axis linear rail carriage support. This removing all flex that occurs in typical gantry plates. I thought I could add bellows to protect the rails if required.

I choose the 16mm ballscrews because my machine is not very long or wide 1000mm, plus it was the maximum I was prepared to pay for leadscrews...

I'm hoping the weight of the steel gantry, will not be an issue. A number of knowledgeable builders who have built steel tube machines all said, if you have good linear bearings and ballscrews it was not an issue. If it turns out to be an issue then I will buy stronger motor. I don't have the expertise to do the math to calculate loads, weight and speed for stepper motor or gearing selection.

 

Thank you Tweakie. Do you have a link to your welded steel machine? I would love to review the design and ask questions!