Cross Slide Screw Support

A few weeks ago I finished a project that I had on my mind for a number of months.  There was a lot of play in the cross slide feed screw on my import bench lathe.  This showed up as backlash in the feed screw – when you grabbed the toolpost and applied force in alternate directions you could see the entire cross slide move back and forth.  Some of it was from backlash in the feed nut itself, but most of it was between the feed dial and the support casting itself.

I tried tightening up the nuts themselves tor reduce the amount of clearance – but then it bound and you couldn’t turn the feedscrew at all.  This wasn’t the best design from the get go.

The first thing I did was modeled the entire assembly up in Fusion to get a clear picture of what was going on – and to give a good starting point for the modification: The nuts aren’t shown on the end of the feedscrew but you can see where the assembly is constrained for axial movement – at the right side on a shoulder machined into the feedscrew itself and on the left side the inner bushing of the dial.  These are just 2 plain bearing surfaces – and they weren’t machined the best to begin with.  No wonder it wasn’t the best!

I thought about doing what Stefan Gotteswinter did.  If this was my main lathe I would copy what Stefan did as it is the best solution by far.  Angular contact bearings are the way to go in this situation.  Since I’m keeping this lathe around primarily for cutting metric threads (the Standard Modern now in the shop doesn’t have a metric transposition gear) I decided to scale back the project and see if I could just stuff a deep groove axial bearing and a roller thrust washer into the space without having to modify the leadscrew, or make up a new dial.

Below is what I came up with:

I incorporated a deep groove ball bearing (6900-2RS) and a 10mm needle style thrust washer on the opposite side.  This required a new housing and the old cast iron bearing support to be shortened up.  The new housing was doweled to the cast iron block for location.  2 counter bored cap screws hold the entire assembly together.  The cross slide screw required minimal rework – a shoulder had to be turned for the bearing to sit against.  I also turned down the shoulder on the screw that previously was a bearing support.

The ball bearing is preloaded using the existing nuts.  Care needs to be taken not to overload the ball bearing as deep groove ball bearings aren’t primarily designed for axial load.  In retrospect I should have flipped the positioning of the deep groove ball bearing and thrust washer around when thinking about cutting forces as the cutting tool pushes away from the work piece.  If I have problems I can always make a new bearing housing.

The cross slide now is super smooth with no backlash due to the support.  There is a bit of backlash in the screw, but I don’t get too bothered by that on a manual machine.  It is significant improvement with not too much effort or time required.

I made a video of the entire project as well:

 

 

Tailstock Die (and tap) Holder

A few months ago I decided I had enough with using my traditional die holder in the lathe and set out to make a proper sliding die holder.  It is a very good beginner project that is straightforward to make and also is one that is exceptionally useful.

I started out with a design in Fusion.  The design consists of 3 manufactured parts, a body, an arbor, and a handle for extra leverage.  The body is designed to hold 1″ dies – a size that I have standardized on in my shop due to primarily expensive.  As die sizes climb the prices move up exponentially and due to that I generally single point large threads.  If you have larger dies the design is very easy to modify to accommodate larger dies.

 

Traditionally most people don’t use a sliding die holder to hold taps.  I’ve always started taps in the lathe using the tailstock.  If the tap is small enough I am brave enough to power tap – being sure to leave the tap a little loose to make sure when it bottoms out it slips to avoid broken taps.  I had the thought to incorporate an inexpensive ER collet chuck into the design to facilitate holding taps.  In this design the ER16 collect chuck stub is held in the end opposite to the die holder with a couple of set screws.

Besides being a pleasure to use with dies, it also works exceptionally well for small taps.  I don’t use the handle when I power tap with it – the handle is really only used for dies.  Now when you are tapping blind holes you can simply let go of the body and the entire body spins.  You can also feel when the tap reaches the bottom of the hole as the amount of force required to hold the body quickly climbs – at this point you simply let go, allow the body to spin and shut the lathe off.

Standard ER collets do a very good job of holding taps in the home shop.  You can get ER collets with an internal square that engages the tap drive but I’ve found it unnecessary for home shop work.  They are also more expensive and harder to find online – most industrial tool supply places can get them.

If you would like to build one yourself I made up a full set of drawings for the shop, and I’ll also provide 3D CAD in the zip file (iges and step):

Handle – (Rev 01), Body – (Rev 01), Arbor – (Rev 01), CAD – (Rev 01)

I also made a video the project:

 

$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.

Fixing a Mill Drill Stand

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.

Shop Made Quick Change Toolpost

A few weeks ago now I finished a quick change toolpost for the Schaublin.

The design is based on Andy Lofquist’s MLA-23 toolpost.  Andy is the man behind the wonderful Metal Lathe Accessories kits (http://www.statecollegecentral.com/metallathe/).  While I’ve never ordered any kits from Andy, I’m told that they are very high quality and are exceptionally thought out.

After quickly considering a Tripan toolpost and changing my mind after I saw the prices on those I ordered a set of drawings for the MLA-23 toolpost.  The original design is for 9″-12″ swing lathes.  The Schaublin is an 8″ swing lathe.  After drawing up the original toolpost in Fusion and drawing up the Schaublin cross slide it was evident that it was too big.  I decided to design a scaled down version, making some changes along the way.

The largest change is in the dovetail size and the shape of the body itself.  I wanted something that would match the Schaublin’s size, but also look, so I manufactured the body out of round material instead of square.  The toolpost is optimized for 1/4″ HSS tools, but 5/16″ will fit.

The internal workings are that of the MLA-23 toolpost.  The design is exceptionally rigid and works very well.  It is also a wonderfully simple in design.  Part of the reason I really like this design is for its simplicity.  I believe the best design is one that doesn’t allow you to take anything away.  This design, in my opinion, is one of those designs.

Some people don’t like that the toolpost doesn’t repeat in angle position – that is once you loosen the locking handle you completely loose the rotational position of the toolpost.  This is a downfall of the design if you truly need rotational position repeatability.  When I work in the shop I’m constantly moving the toolpost around to allow for tool clearance.  So much so that I made a handle for my Aloris clone on my 10×18 lathe a number of months ago.  I do have provisions in the design to allow for graduations on the base to allow for visual rotational positioning.  We’ll see if I add it.

The build was interesting and fun.  I learned a number of things along the way including how to cut dovetails on the shaper.  It took a bit of time, but it reaffirmed the very useful nature of having a shaper in the shop.  Instead of waiting for a dovetail cutter I could grind up a simple tool and cut nice dovetails, at any angle, and get a super finish.  I’m told you can build the entire toolpost with a lathe, but there is a fair bit of milling work so even a mini mill would be a huge help.

Since the design borrows heavily from Andy’s design I don’t want to release drawings.  What I’m planning on doing is forwarding a set of drawings to Andy to include with his prints if he is interested.  So if you want to build the smaller version, which is a perfect size for the mini lathe, send me an email and I’ll try to get you a set of drawings.

I made a build video of the entire toolpost in montage style format as well.

 

Schaublin 102 is Making Chips!

Although I’ve talked about it with Max on the podcast, I’ve never announced on the blog that I picked up a made in Switzerland Schaublin 102.  102 is the turning radius in millimeters (about 4 inches).  The lathe was in pieces, but in very workable condition.  I dragged it home and it sat for a few months until I found the time to get to working on it.

This week I finally managed to get the 102 making chips.  It took some work mostly in the drive area.  I didn’t have access to the proper voltage to drive the existing motor so I decided to replace the original Schaublin motor with new 3/4 HP Baldor that I picked up a year ago for $50.  I also wanted to keep the mechanical variable speed drive working.  I could have got the old motor rewound, and I might do that some day, but the $800 that I was quoted was a bit rich.

After modelling up the existing motor in Fusion I designed up a pulley to fit the Baldor, spacers to place the new motor in the same location as the old one and a motor mounting plate.  I used old school methods to make up a plate to mount the VFD and associated electrical components.

I made a montage type video of all the work:

I was pretty happy with how it turned out.  Here is an animated gif showing a test cut that I did with the lathe:

Aside from making up the required parts, I spent a fair bit of time cleaning out the bed, cross slide, tailstock and the interesting air – oil lubricating unit for the spindle bearings.  I also have several hours fishing the air – oil lubrication lines back into place in the headstock.

I’ve never used a plain turning lathe before, and quite frankly until I did I thought they were a bit of a joke.  In the past no carriage or leadscrew caused me to immediately write off plain turning lathes as useless machines.  Nothing could be further from the truth.  In fact, as I used my import lathe more (which has a carriage and leadscrew) I realized that I do 80% of my work without such features.  If you have the chance to pickup a plain turning lathe in good condition, jump at it!   Many people devalue such machines and as such you can sometimes get a very good deal on a lathe that is exceptionally capable – and a joy to use.

Next up is a proper toolpost for the lathe, a backing plate for a Buck 6 jaw chuck I picked up, and probably a faceplate.  That is unless I manage to pick this stuff up used somewhere.  I really don’t count on that happening though.  Parts and associated tooling for Schaublins usually demand high prices.

 

 

Pentel P209 Teardown

wrTie has begun!

To start off my titanium mechanical pencil build, called wrTie, I decided to teardown a number of different mechanical pencils for inspiration and design ideas.  I find the mechanisms in mechanical pencils very interesting.  I also find the manufacturing processes that are used exceptionally interesting.

Here is a teardown video of my favourite mass produced mechanical pencil: the Pentel P209 (0.9 mm version).  The Pentel P20x series (there are 0.3, 0.5, 0.7 and 0.9 mm models)  has been around for a long time.  It is exceptionally well made given the price point it is hitting and the parts involved.  There are 12 parts in total, including 5 fully machined parts.  A number of the parts require plating.  There are 2 parts that are molded out of plastic.  And then it has to be assembled!  You can buy a Pentel P209 for less than $5 in the United States and less than $7 in Canada.  That’s actually pretty crazy considering this pencil contains machined parts and even more so once you consider that Pentel is probably selling it to it’s retailers for less than half of what they are retailed for.

https://youtu.be/tM4h61_BLKQ

The heart of the Pentel 200 series is a removable fully contained feeding cartridge.  The cartridge features a number of machined components in the feeding mechanism.  The components are probably massed produced on swiss style screw machines (a lathe but instead of the carriage moving the spindle moves in the Z direction – often called sliding headstock machines).   These machines could be cam actuated screw machines or they could be CNC controlled units.  CNC swiss style machines, like the ones produced by Star or Citizen, are really interesting machines.  Here is a video of a Citizen L20, one of the more popular CNC swiss machine that you will find today:

The Pentel P209 cartridge has been used in a number of titanium mechanical pencil builds on Kickstarter.  I can’t confirm it directly as I haven’t purchased one, but check out this project (you have to scroll about half way down and you’ll see a picture of what looks to be the Pentel cartridge: https://www.kickstarter.com/projects/cogent/titanium-mechanical-pencil-and-titanium-pen.  Given the Pentel’s design, you could easily make a new mechanical pencil by machining a new outside body for the Pentel.  I won’t be doing that because I think it is too easy!