Over 6 months ago now I finally finished a pair of yo-yos I made for family friends who gave us a wagon for our kids. The wagon was a very well made wagon and I wanted to make a special gift for the family in return. I remembered how much I enjoyed yo-yos when I was a kid so I decided to make up one for each of their 2 girls.
The design is very straightforward. Essentially it is 2 aluminum halves with a tool steel axle. I chose to make the bearing / bushing out of some Teflon I had in the shop. You could easily modify the design to use the very common rolling element bearings that so many yo-yos utilize these days. The trickiest part of the design is sizing the o-ring that sits in each of the halves. The size and cross sectional area of the o-ring used determines how easily (if at all) the yo-you will return to your hand. If you remove the o-ring completely the yo-yo may never return to your hand and probably will require what is called a “binding” trick which causes the yo-yo to recoil its string. Since I wanted these yo-yos to be easy to use for beginners I sized the o-ring so the yo-yo will return with a easy flick of the wrist.
The project made heavy use of the 5C collet chuck that I previously reviewed. The chuck worked out very well and the soft 5C collets that I used made the job much easier and quicker than it would have taken using the old 4 jaw standby.
I chose to press in 12 pieces of brass on the outer rim for added mass where it is needed most. Besides making up 48 pieces of brass for 2 yo-yos the process was very easy. After the brass was pressed in I cut the outside radii with a custom form tool I made up in the shop. I also made a video of making the form tool. You can watch that video here:
Besides the custom form tool for the radii, there were a number of other tools I ground up to make this yo-yo. The project once again highlights the basic home shop need of being able to grind high speed steel tools. If I had to purchase all the cutting tools I needed for this project the cost would have been significant.
I also did a full build video of the process. Many thanks to Megan for recording music for the introduction.
If you are interested in the drawings you can download them here:
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.
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.
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.
If you listen to the podcast you already know that I purchased a Rong Fu Mill Drill. While some people have issues with the round column, the mill drill is a significant step up in machine capacity and machining performance when compared to the X2 mini mill.
For those unfamiliar, the Rong Fu Mill Drill looks to be a heavily modified drill press. There are several size variations, but most utilize a R8 tapered spindle with provisions for a draw bar. The dovetail table has a relatively large travel of about 450 mm (over 17″) and 200 mm (just under 8″).
While there is much debate on the origins of the Taiwanese mill drills that started showing up in the 1970s, the most probable explanation is they are simply rather crude copies of the Fehlmann mill drill machines. Fehlmann is a Swiss machine tool manufacturer and they still build a number of mill drill machines, although I suspect you if have to ask the price you cannot afford them. Besides the very similar appearance, the main reason I think the Rong Fu mill drills are copies of the Fehlmann is primarily because of the tapered gibs on the Rong Fu table. Fehlmann being a Swiss machine tool company in and of itself is another telling reason why they were copied.
Round column mills are not just limited to two companies. Emco also manufactured several round column mills around the same time as Rong Fu started. A German company also manufactured a nice home shop mill drill branded as Ixion around the same time or slightly before the Rong Fus started flooding the home shop market.
The Rong Fu mill drill I purchased came with the typical flimsy tuna can stand that is oh so common on import machine tools. I did not purchase the machine new and the previous owner was selling the stand with it, otherwise I would have passed on the stand and just built one. Initially I was going to weld up a new stand out of 2×2 steel tubing, but then I thought could I just dump a bunch of concrete in the bottom and kill 2 birds with one stone; adding weight and rigidity? That and I find concrete a very useful engineering material in the home shop from previous antics.
And that’s exactly what I did. For less than $75 and one day’s home shop work, which is less than what the material alone would have cost for a tubing stand, I now have a rigid machine tool stand.
I’ll be posting further on the mill drill as I use it, but so far it has been a great addition to the shop.