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MachinistBlog.com

Plans, projects and how-to's for home machinists

I Bought a LONG Shop Vacuum Hose

I just bought a 20-foot hose for my shop vacuum and I wish I’d done it decades ago.  I never realized it before, but my shop vacuum is probably the tool that I spend the most time using and a longer hose makes it much easier to use. 

The hoses and electrical cords that came with my shop vacuums aren’t unreasonable short, but over the years I’ve spent many hours moving my shop vacuum from one electrical outlet to another in order to reach every corner of my workshop.  I’ve also pulled the hose out of it or tipped the vacuum over innumerous times while trying to move it by pulling on the hose.

With the new hose, I can leave the vacuum in one location and still reach every corner of my garage workshop.  It will also let me vacuum the interiors of two cars without having to first plug my shop vacuum into an extension cord and then move it around the cars four or five times.  

Buying a shop vacuum hose can be difficult and a little risky because there are a variety of different hose diameters and the ends come in different sizes.  I purchased a 20-foot Cen-Tec Systems 92707 Premium Shop Vacuum Extension Hose from Amazon for $34.86 and I’m very pleased with it.  It is what I recommend you buy if your shop vacuum accessories fit a 1-1/4 inch diameter hose. 

The intake end fits the intakes of my Shop-Vac brand vacuum, two Sears shop vacuums and a Ridgid shop vacuum, even though these vacs came with hoses ranging from 1-1/4 to 2 inches in diameter.  The accessory end fits all the 1-1/4 inch extension tubes and accessories that I’ve acquired over the years. 

I was surprised to find that the ends on this, and many other long hoses, screw on and off; and that there is wide variety different size ends and adapters that you can buy to fit your equipment.  The problem is that the size descriptions for fittings and adapters are not always clear.  Fittings also come in both US and metric sizes, and sometimes the sizes are close enough to work because of the taper.  For example, a 32 mm inside diameter fits on the ends of my 1-1/4 inch hoses.

Hoses restrict air flow and so the the longer the hose is the less suction you’ll get.  This can be offset by using a larger diameter hose.  My new hose has plenty of suction, but I do wish I’d thought of this and checked to see if I could have bought a 1-1/2 inch hose with the same size ends as this one.  I’m sure they’re available and they probably don’t cost much more.

I’d never thought about buying a longer shop vacuum hose because I thought that shop vacuum accessories were/are obscenely overpriced.  But I needed a long hose to reach the dust shoe of my new CNC router.  This hose works great with it but I did have to design and 3D print an  adapter for it.  I will be sharing the .STL and Fusion 360 files for that in a later post. 

Dial Indicator Helps Set Z-axis Height

I bought an old Federal dial indicator from a retired machinist that had a big flat donut-shaped magnet glued on its back.  I almost passed it up because it was kind of ugly, but it has turned out to be one of the most useful tools in my workshop.  It is particularly useful for adjusting the Z-axis height on my Harbor Freight mini-mill.

I’m a little mistrustful about dialing in the height because of the huge amount of backlash in the Z-axis.  So I often stick my DI on the column and use it to set the height or to double-check the dial and make certain I haven’t miscounted the number of turns I’ve made.  It only has a range of 1-inch but that’s all I need most of the time.

It was really helpful last night when I needed to remove a very small amount of metal using a fly cutter.  The indicator showed that the head was dropping another 3-thousandths when I tightened the gib lock (which is one way to protect yourself from the mini-mill’s infamous “head drop problem“).  I hadn’t experienced that problem before and I hope the gibs just need to be adjusted.

A couple of potential problems

To get the most accurate reading your indicator’s plunger needs to be perpendicular to the head.  Instead of eyeballing it I’ve thought about building a magnetic mount for one of my other indicators that would slide up and down against the column’s dovetail.  It would make it easier to position the indicator and ensure it’s always perpendicular.  I didn’t have a big enough block of aluminum the last time I was going to make one and this morning I was wondering if it would be easier, cheaper and faster to just buy another column stop and modify it to hold an indicator.

And lastly, a more experienced machinist once told me you can ruin a cheap poorly-made dial indicator by sticking a magnet on it. Continue reading Dial Indicator Helps Set Z-axis Height

How I tram my mini-mill

This is how I tram my mini-mill.  I think the method I use is fairly common, although I may use slightly different equipment than others.  There are other ways of doing it and some people have strong opinions about which way is best.  I’ve included links at the bottom to some interesting discussions I found if you would like to learn more.  If you don’t know, tramming is the process of adjusting the mill’s column so the spindle is perpendicular to the table.

By the way, this procedure only trams the X-axis.  Unlike most other mills, the mini-mill’s Y-axis is not adjustable, although there are ways of doing it if you’re willing to go to the trouble.

My Equipment

  • A matched pair of 1-2-3 blocks
  • A digital dial indicator
  • The fine-adjustment arm from an inexpensive magnetic base for a dial indicator held in a 5/8-inch cross-drilled piece of drill rod mounted in a collet

I started using the arm from a magnetic base because it was the quickest and easiest way to mount a dial indicator so I could read it from the sides of the mill.  It replaced a home-made one that had the DI facing forward (good) and to rear (hard to read).

If your mill vise is big enough you can measure on the top of it with a dial test indicator (DTI) and tram your mill that way.  The vise shown in the picture is probably big enough to do that.  But the screwless precision vise I often use isn’t, which is why I use the 1-2-3 blocks, a trick I learned from someone else.  The blocks will also allow you to tram your mill without removing the vise.  I also believe you can get better results by taking your measurements farther apart.

For Best Results

Before you get started you should swing your indicator from one side to the other a few times to make certain you get repeatable measurements and there is no “play” in your setup.  You should also center your table under the spindle and make your measurements on its center line and at the same spots each time.

You should know that tramming your mill’s table does not guarantee your vise will hold your work pieces square with the spindle.  It should if it was made properly.  If it doesn’t you should find a way to fix it, consider getting another one or tram your vise instead of the table.  I’m talking about your vise being square with spindle, not with the table.  That’s also important, but it’s different topic.

One way to check your vise is to tram your table, mount a long parallel in it, and then measure at the ends of the parallel with your indicator.  It should be just as perpendicular to the spindle as your table, or pretty darn close.

It’s Easier with a Digital Dial Indicator

In the past I’ve always trammed my mill using a traditional dial indicator with a needle and dial.  Sometimes it would take me just 2 or 3 minutes but other times I’d be scratching my head for 10 or 15 minutes and wondering what the heck I was doing wrong.  It was usually because I’d gotten confused reading my “analog” indicator, which is easy is for me because as an amateur machinist I don’t use one very often.  So the last time that happened I took my old indicator off and replaced it with the new digital dial indicator I’d bought from Harbor Freight for about $25 (with a 20% off coupon).  It instantly put an end to my confusion.

The Procedure

The procedure is simple with a digital indicator.  Swing your indicator to one side and zero it.  Then swing it to the other side.  If the measurement is “negative” then push the column toward that side half the distance shown on the indicator.  If your measurement  is “positive” then push the column away from that side half the distance shown.  Then zero the indicator again and swing it to the other side to check your work.  You want to try to get the same distance on each side,  although I wouldn’t worry too much if you’re only off a thousandth or so over a good distance (my setup takes measurements about 10-inches apart).

If your indicator has a needle, then use it to find out which side has the shortest distance between the indicator and the table, and then “zero” it or write down the measurement.  Then swing it to the other side, calculate the difference in length and push the column toward that side half that distance.

Before you can adjust the column you’ll obviously have to loosen the big nut on the back of it a little.  There’s a good chance that the column will move slightly when you tighten it again, so re-check the tram.  I’ve found you can minimize that if you loosen the nut just enough to allow you to move the column by gently tapping it with a rubber mallet.

More information

CraftKB: How to tram a Sieg X2 mini mill

Practical Machinist Forum: How to tram a mill for best surface finish / flatness?

Wire Rack Attack!

This short video shows a simple low-cost method for organizing small reels of wire.  I found it on Makezine.com’s blog, which recently featured a couple of our articles.  One was Mikey’s contest winning essay and the other was Nate’s short article about some free plans for a Watt-style steam governor.

I’ve been working very hard lately at reorganizing my workshop and getting rid of stuff that I don’t need or rarely use.  I really need to make more space because I now have two lathes, two mills and a couple of friends who have been coming over to use them.

Random Quote

You’re not going to get it done playing computer games or surfing the net.

— R. Roll