Diamond Dresser

For Christmas a few months ago I made a diamond dressing tool for my brother in law.  He is a woodworker and uses his bench grinder for the initial sharpening of various wood working tools.

The tool is made up of 4 parts.  The body is a piece of steel with an angled lip (one on each side) that is used as a guide against the tool rest on the grinder.  It has a threaded hole for the diamond.  The diamond is an industrial diamond held in a steel rod – commonly used in surface grinding dressers, modified with threads along most of its length.  There is a lock nut and o-ring (to provide some cushion when tightening the nut down) and a handle nut to adjust the distance from the lip to the edge of the diamond.

The tool is useful for most sizes of standard bench grinders as the body has 2 different lip offsets.  The threaded diamond is also allows for generous positioning.

After giving him the tool I explained a few of the benefits of such a tool versus a traditional spur style tool:

  • The amount of grinding wheel material removed is easily controlled as the distance on the single point tool is adjustable.
  • A single point diamond tool does a better job at getting the wheel round in the first place.  This is because the forces involved are significantly less than traditional spur type tools, or even the newer T style diamond tools.  Forcing traditional tools up against the wheel isn’t a very steady process and the entire tool floats on the surface of the wheel.  In addition your hand can move back and forth with the high and low points on the wheel.  As such I’ve found single point tools create a wheel that is rounder, which helps with balancing.  (Grinder balancing always happens after a wheel has been dressed).
  • Unlike spur tools or the cheap T style dressers a properly used diamond tool lasts a long time on a bench grinder and also is very durable for various wheel materials.

After Christmas I finished up a tool for Max over at the Joy of Precision:

I made up a full set of drawings of the tool if you would like to make one yourself:

Body – (Rev 01) Diamond – (Rev 01) Handle Nut – (Rev 01) Lock Nut – (Rev 01) Dressing Tool – (Rev 01)

I’ve also had a fair bit of interest in people asking if they could buy one of these tools.  I’m making up a number of them for others so if you are interested send me an email: justin@thecogwheel.net.  I’ll be posting additional information shortly.

As usual I made up a video of making the tool and it also shows how I use it:

 

 

Vise Clamps and 1 Hour Red Rust Bluing

Let’s rewind to the summer when I purchased the Rong Fu milling machine for the shop.  The mill included an exceptionally well made French made Sagop milling machine vise that had a bit of wear but was very usable.  Up until this point I have never heard of Sagop before.

A quick search revealed a basic corporate webpage. It appears that Sagop is still in business and still manufactures a line of workholding products.  The vise that I purchased is the smallest of their precision CNC milling vises, a 100mm 800 series vise.  The construction of the Sagop is very similar to the Bison precision CNC milling vises.  I was also floored to learn the purchase price of this vise.  It is listed over 1000 euros with the swivel base – a number that is rather shocking when you consider that it is sitting on a Rong Fu milling machine!

The vise came with the swivel base – a very well made turntable base that allows for 360 degree rotation.  A very handy feature in some situations, but for most of the work that I do I usually just bolt the vise directly to the table.  This takes up less table space and is also more rigid.

Strangely the vise did not come with any way to mount it to the table.  Up until this point I had been using some of those standard import clamps that are sold everywhere.  This wasn’t the best solution as these clamps are quite bulky and don’t do the best job of holding in situations like this.  So set out and designed up some new clamps to be made.

But first I searched to see if I could find drawings of the vise and / or the swivel base, not only for this project but for future ones.  While not directly advertised on Sagop’s website, I managed to find the drawings for the vise and the swivel base:

Sagop 800 Series Vise Drawing  Sagop 800 Series Swivel Base

I modeled the clamp up in Fusion and made up a drawing of it based on the dimensions I found in the above pdfs.  Now some folks at this point say CAD is a waste of time for such simple projects, and it maybe for them.  But I’m actually quicker at modeling something up in CAD than I am drawing up a sketch on paper so for me I usually start with a 3D model.

The clamps are designed for 3/8 cap screws.  I then made up a shop drawing for the clamps:

Sago Vise Clamp – (Rev 01)

Making the clamps was a very straightforward process. The most interesting part was when I used the 4 jaw chuck in the lathe to counterbore for the cap screws – I haven’t invested in any counterbore tools yet for cap screws.  I need to quit being so cheap.

When they were finished I started to wonder about how I was going to prevent them from rusting.  Rust is a very real problem in home shops, and in particular my shop as I live in a climate that is somewhat humid and has significant temperature swings.  If you are willing to deal with plating shops you might be able to find a shop to do a zinc coating – but for small one off parts it is often impossible on a budget as most plating shops have a minimum charge that far exceeds what home shop machinists can afford.

I have considered cold bluing products in the past as a simple method to provide some rust protection on parts.  In Canada cold bluing is a bit harder to procure than south of the border, and is is also somewhat expensive.  So I started to read up on other processes.  Hot bluing looked interesting, but involves some nasty chemicals.  Rust bluing looked promising but it seemed like a long process – you had to wait around for the rust to happen.

I did some more reading and I recalled an experiment we did in high school chemistry involving a mixture of hydrogen peroxide and salt applied to steel wool. The hydrogen peroxide and salt rusted the steel wool so quickly that you could measure the temperature change. I then did some further searching and I found a fellow Canuck who beat me to the idea of quickly rusting parts using hydrogen peroxide and salt: https://mypeculiarnature.blogspot.ca/2014/08/quick-rust-bluing-back-in-black.html

The process is very simple:

  1. Thoroughly Clean parts using a good degreaser.  This step is very important!
  2. Etch parts in acetic acid (common household vinegar)
  3. Rust parts using a warm hydrogen peroxide salt mixture.  You can either fully immerse the parts or brush the mixture on.  I mixed it up about 1/4 cup peroxide and 2 tablespoons of salt.
  4. Fully submerse parts in boiling water and watch red rust turn to black oxide.
  5. Lightly wipe or wire brush parts.
  6. Repeat steps 2 through 5 until you are happy with the coating.
  7. Dry parts and oil

The final result is a nice black oxide coating that helps protect against rust and looks great:

I made a video of the process, including the making of clamps:

 

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:

 

The Future is Here: Introducing a Laser Bandsaw

A few months ago Max and I recorded a podcast where Max and I theorized on the what the home metal shop of the future would look like.  The podcast idea was inspired by the Making It podcast hosted by Jimmy Diresta, Bob Clagett and David Picciuto where they talked about what they think the future maker workshop will look like.  During the podcast Jimmy, Bob and David mentioned the idea of a laser bandsaw – something that Max and I also talked a bit about on our podcast.

A month or so after the podcast Rod Shampine reached out to me to talk shop over the phone one night.  I had a very enlightening conversation with Rod, who is an exceptionally gifted mechanical engineer with over 50 patents.  Rod also has his PhD and has worked on some exceptionally interesting projects – both on the job and for hobby.  He is an active home shop machinist as well.  Over the last few years Rod has done a significant amount of work in the 3D printing world – he is very active on Thingverse and also has did a significant amount of work on 3D printers themselves.

In the conversation Rod told me he had acquired all the hardware to put together a laser bandsaw prototype.  At first I thought he was making a joke, but he went into specifics about safety, power supplies and the actual laser itself.  Rod certainly had a workable design flushed out – one that both had us very excited.

In December Rod sent me an email that he had finished his laser bandsaw.  It could only really cut paper and balsa wood but to my knowledge it is the first working prototype of such a device.  Obviously a laser bandsaw is exceptionally hazardous – particularly to your eyes.  Rod pointed this out numerous times.  But with proper eye protection and proper design a device could be made to work.

Shortly afterward Rod posted his working prototype on Youtube:

So thanks to Rod the future is now here.  I’m watching with interest to see where this all goes.

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!

 

 

 

wrTie

Great ideas begin in the simplest forms.  A sketch on a napkin.  A doodle on a scrap piece of paper.  A few words to solidify the idea that has been formed in the mind.  And the sketch or doodle, the short sentence or scribble, all start with a pencil.  That’s why I’ve thought a fitting project for 2017 is WrTie, a titanium mechanical pencil.

This project symbolizes my desire to do things different.  WrTIe will be a product designed to last a lifetime and pass onto your kids (like that pocket watch you received from your grandfather), a project that challenges design and manufacturing skills, and my desire to be an inspiration for everyone working in their garage.  And that’s where great ideas start.

The real question is can a small shop with manual machines and one man design, prototype, and manufacturer something so simple … yet so complicated?  This is a product made with a material that is difficult to manufacturer with even the best equipment.  And I’ve never machined titanium.  Not even once.

What will follow over the year is a series showing my progress on designing, prototyping and manufacturing a mechanical pencil made from titanium.  There will be product tear downs, unique designs, tiny o-rings, CAD software, research, guesswork, calculated risks, material investigation, tool design and selection, deep hole drilling, tiny machining, the help of friends, many failures, frustrations, lessons from craft beer, and I hope in the end success.

I haven’t written or designed anything.  This is not scripted.  This isn’t a Kickstarter campaign.  Through the power of video you will be coming along for the journey, every step of the way, watching ever failure, and every success.  I want to learn and do something productive, and I hope you do as well.

And in the end if it all works, I hope to have something special that I can use every day.  The drawings, the lessons learned, the tricks discovered, will all be here.

To show your support, I ask you to subscribe.  I will start in early 2017.

Now I need to get this VFD put on my lathe.