Tag: Measuring

$200 Shenzhen DRO (JCS900-2AE)

About 6 months ago I purchased a digital readout off eBay for the Rong-Fu mill drill. Originally I had planned to purchase either iGaging scales or standard import calipers and utilizing a tablet based DRO. Once I started looking at prices however I was shocked to find that for less than the price of either the iGaging scales or the import calipers I could have a full blown 2 axis DRO complete with proper glass scales.

I went ahead and ordered the scales off a eBay seller. It was a typical Chinese eBay seller that sells everything from DROs for machine tools to various useless cell phone and house gadgets. The total for the order was around $200 USD plus about $30 for shipping. I then communicated the scale lengths I needed via email. In about 2 days I had a shipping confirmation including a tracking number.

I was excepting to wait about 3-4 weeks for the shipment to arrive, typical of most stuff ordered from China. I was shocked at the end of the week when I received an email from DHL that my shipment was to arrive on the following Monday – about a week for the entire process! Sure enough Monday afternoon a DHL driver dropped off the 2 boxes.
The one box contained the DRO – a JingCE JCS900-2AE 2 axis DRO unit. The other box contained the 2 glass scales both of proper length. Also included was a large amount of hardware, mounting brackets and associated items you would need to install the DRO.

I spent the next few days thinking about how to mount the scales. The X axis was easy – I decided to mount it to the front of the table using the T slot already present. I thought about mounting it to the back of the table but I didn’t want to loose any Y axis travel. The Glass scales are rather bulky – something to note if you are considering installing them on a smaller mill like the X2 mini mill. The Y axis was a bit of a different story – there really isn’t anything to fasten the scales to. I decided to make up a bracket to hold the Y axis scale. That took a fair bit of work to do.

Y Axis Scale (behind the fabricated bracket)
X Axis Scale

After mounting the scales and trying out the DRO I also fitted a inexpensive import digital caliper to the quill to get a .001″ resolution readout for Z depth. This also took a few hours to do properly. 2 brackets were made out of aluminum to hold each end of the caliper. I modified the caliper using a Dremel tool. I drilled mounting holes using a standard off the shelf masonry drill bit – a poor man’s way of drilling hardened steel. High speed steel usually won’t touch hardened calipers.

Hard Drilling Using a Masonry Bit

After using the DRO for 6 months I can say that it is a very good unit. I haven’t had any issues. As far as accuracy and repeatability is considered, I really don’t have the proper measuring tools to qualify the DRO but I will say that I tested it using a dial indicator over the travel of the table. At each point where I tested the DRO it corresponded to the dial indicator – within at least .0005″ (as best as my judgment permits). I also ran the table up against a hard stop several times to test the repeatability and each reading was easily within .0005″. I probably should do a proper gauge R and R study on it, but just with the general testing I’ve done it’s easily within .001″. And to be honest doing work closer than .001″ on a Rong Fu mill drill is unreasonable.

I filmed and edited a number of videos showing the install and finally a video review of the DRO.  The first video shows the hard part: the installation of the Y axis scale.

The second video shows the installation of the X axis scale and also the mounting of a digital caliper on the quill.

The final video is me talking about the DRO itself and contains much of what is written here.

If you are interested in reading the manual, I scanned a copy of it and it is available here.

One thing to note is that you will get little to no support with the DRO. To me this isn’t a big deal at all when you consider the price. The next closest DRO in price in the North American market is approaching 4 times the cost. And the unit looks suspicious like this unit. If something breaks I am willing to try and fix the unit myself or simply replace it.
If I had a high end knee mill I would probably buy a Mitutoyo DRO and be done with it. But putting a Mitutoyo DRO on inexpensive import mills is a bit like putting lipstick on a pig.

It was a $200 well spent. Having a DRO on a milling machine is exceptionally handy. I won’t say it is a necessity, but it greatly improves your efficiency – especially on larger mills or making larger parts. Time will tell how durable the unit is but I think it is an excellent addition to a home metal shop.

Height Gauge Depth Arm

In the shop I have a 2 beam dial height gauge that I use a lot for measuring and general layout work.  As far as measuring equipment, it is my favourite tool to use, even though I would want a micrometer and a caliper before a height gauge.  Once you get one you’ll wonder how you got by without one.

Most height gauges come with a tool for measuring flat surfaces, and for scribing.  To get the most out of the gauge you need a depth arm – basically a pin in an arm, for measuring depths.  I needed one to measure up a motor face so I can get a 3 phase motor mounted on my lathe – one of those projects to complete a project sort of deals.  I decided to make one up instead of buying it:

I made most of the arm on the shaper and used a gift from Max over at the Joy of Precision to bore the hole for the pin.  The boring head Max made is the star of this show.  It is the perfect size for the mini mill.  It is one of the best designs for a small boring head I’ve seen, and used.  The adjusting dial is a tad small but once you get a feel for it adjusting it is easy.  It’s also great because you can bore small holes – saving you from buying a lot of reamers.

The pin was turned between centers and was within .0004″ over the length – something I was very happy with.  The deviation was in the centre of the pin.  The pin sprung between centres a bit when I was cutting – aside from using a traveling steady there isn’t much you can do here about that.  The beginning diameter and end diameter were essentially the same within .0001.  I probably didn’t need  that much precision but I wanted to dial in my tailstock anyway.  At the end of the pin you can screw in standard dial indicator ends using a #4-48 thread.

I made the screw out of brass because it looks nice, and doesn’t mar the pin.  I usually don’t turn that much brass so I was reminded how easy it is to work with.

Here is the drawing for the height gauge arm.  I will be sharing all the projects in Fusion at some point and I’ll post a link.

Height Gauge Arm (Revision 01)

If you are looking to get a height gauge, do yourself a favor and go a dial one instead of a digital one.  Even though the dial on mine is graduated to .001″, you can actually measure much closer in the home shop with it.  Notice I didn’t say in the shop – in a professional environment I get that you need hard numbers and ‘guessing’ at the measurement is very poor practice.  Verniers are also good but I find them slow – probably because I don’t have enough practice.