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View Full Version : Impressions/add-ons Mini/Micro mill [long]



Mr-Mike
12-01-2015, 01:20 AM
DISCLAIMER: 98% of you will realize 0% benefit from this post


Some may recall, a couple of months ago (mid-Sept.) I was a complete neophyte. Now, probably a just below average beginner with only few simple projects under my belt. I purchased a Taig 2018ER and then found this forum and started asking questions, after the fact. All comments provided were immensely valuable and spot-on, including the critical ones. I can NOT say I would have made a different choice based on the factors at the time, however the limitations of this machine are real and frustrating. The upside is that the ROI is good considering my minimal usage, it is a great and forgiving learning platform and it take very little room.


Here’s what’s been done to the Taig:


DIY air blowing – Blowing chips out of the cutting path (plus the cooling effect) has been a ‘breakthrough’ for results and clean-up (almost eliminates lubrication with small/soft stuff – suitable to this mill category). Powered by an Alita AL-40 linear air pump (perfect air stream for a ¼ inch nozzle with a ½ inch loc-line tube) and extremely quite; no doubt coolant can be easily added). No more brushing chips out of the path and eating bristles and ruining the results.


Made a scrap metal long T-Slot insert used as a mount for the air nozzle – super easy disconnect convenience. The nozzle is zip-tied to the to insert and it is simply slid into the t-slot on the side of the spindle block. After cutting, I simply slip it up and off to inspect (no repositioning of the nozzle needed once adjusted for the work and tooling), and right back on in a matter of seconds.


A decent, heavy vise –probably the most important component. Got a 3 inch screwless (more on this later) and an assortment of clamp components. Related must haves include: parallels, dead-blow hammer and machinist squares


A 4” Rotary table for making nice arcs and increasing capabilities a little. It’s a Phase II. It’s heavier than similar units, yet doesn’t stress the mill table or its movement. It needed extensive clean-up, disassembly and adjustment but now seems to function nicely with minimal backlash. Operation after tuning is decent. The layout of the Phase II leaves a little to be desired. While in its vertical position, there is little room in front of and under the turntable to clamp it down. I chose to make a simple mounting plate for that purpose. I also drilled-out and tapped the existing threaded mounting holes in the alignment groove on rotary table’s vertical orientation base to accept much larger bolts – from a wimpy #4-48 screw size to a full ¼” - 20. (incidentally, the original threaded holes were shamefully out of alignment – typical Chinese QC).

A 3” 3-Jaw centering chuck and adapter for the rotary table. The chuck needed disassembly and adjustment, and the gears inside were virtually dry (the little residual grease was more like tree sap). I cleaned them up and re-greased them. The adapter itself needed a little work too, to get the registration hole fit – the adapter’s raised hole diameter was a thou too big and needed some careful filing/sanding to fit the rotary table. I passed on getting a tailstock due to limitations in turning with the chuck. While weight on the table is now significant (~20lbs), the added mass seems to be a plus and table movement is still smooth.


DIY front chip shield held on to the end of the vise with a magnet – this turned out to be brilliant when the vise is perpendicular to the table. Effortless to pop on and off as desired. I yanked a very strong magnet from a standard computer hard drive and cut a 6 x 20 piece of vinyl (cost: <$1). Also, a long spring over the spindle head to keep the rear chip shield extended and tidy :)


Another scrap metal support that slips into the T-Slot on the right of the lower cross-slide table (Y-axis) to hold the rear rubber chip shield in an elevated position so it both deflects chips and stays clear of the ‘Y’ hand wheel (got really sick of smacking that rubber flap 5000 times every time I used my mill. Obviously the shield travels with the axis – nice.


http://www.boundlessaccess.com/mill2.jpg


http://www.boundlessaccess.com/piece1.jpg


http://www.boundlessaccess.com/mill1.jpg


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Here are some random thoughts:


I will start with the aforementioned screwless vise. I made a mistake with the first one I ordered. I has rows of round individual mounting holes along the sides of the base. I bought a second one, but with long square channels along the sides (and use standard clamps) which is far better. With the round holes, you snug the vise down with the clamps and square it, the vise will lose ‘square’ when you crank it down securely. Loosening slightly to re-square causes the clamp pegs to shift in the holes again. It’s the curved contact points that imparts this behavior.


Taig specs suggest the tilting column goes to 90 deg – they are joking right?. While this is true, stop and consider where the column’s mounting axis is and you will see that 90 degrees is absurd! Any rotation beyond 60 degrees or so will put the spindle below the table (varies with table height adjustment). Suffice to say, 90 degrees is well below the table.


I disassembled the table and cross-feed (X & Y axis beds), re-bedded/re-adjust the gibs and leadscrew(s) fittings. There was room for improvement


Pivoting column Z axis, it simply can’t be too tight (wonder what torque manufacturers recommend?). I tried to measure the torque I am using but my 7/8ths socket wasn’t deep enough


Aside from certain drilling operations (for example a chuck and larger bits), the Z axis travel is plenty sufficient for most work, it’s the y-axis that is limiting. Make sure the vise travel is sufficient in all directions. Positioning the vise (especially a larger one - max IMO 7.5”) so it’s not in line with the column helps a lot


I tried using the measurement index dials on the mill axis but being a manual machine without DRO, laying out the work and scribing lines is more proficient. Due to this, the edge finder gets no use.


Fly-cutters seem to be the best option when a cleaner surface is desired. On the other hand, slitting cutters are just too much for this machine


A little manual mill is challenged when it comes to making perfectly mated surfaces – pieces with truly square and precisely mated edges, especially mating 90deg cut angles a. If that goal was a more common one for me, I would be buying a more massive, solid column mill to be sure, better yet a grinding machine. I achieved poor results when making a plate with a machined-in guide rail. Struggling to ‘true-up’ my work, I tried using a dial test indicator to locate ‘high’ spots, results were ‘meh’ with a cheap Fowler. Then I inked the entire worked surface and fit it in place – jiggled it a bit to create score marks, then sanded those areas. I still wasn’t satisfied. I did discover that a small piece of Al bar stock (2x1x3/4) makes a great little sanding block. Using a dial caliper also still unsatisfactory. I decided to check the squareness/tram of the mill AGAIN. BINGO! Though I was certain my set-up was square from my last tramming procedure, it turned out to be ‘out’ by a hair – literally about a ½ thousandth. A simple machinist’s square revealed the non-conformance. I am left with a distaste for ‘tilting column’ mills and I can say quite definitively that flat surfacing is well beyond this mills capability. Ironically, I ended up abandoning that plate and went with a different more simplistic design. Seems I am very good at making scrap material! The moral of the story, check the squareness EVERY time a new piece is mounted (5 sec with a machinists square can save hours).


I replaced the Fowler X-Test DTI, it’s junk IMO. Skittish movement of the needle and failure for it to return reliably and repeatedly to the ‘zero’ is a showstopper. I bought a Brown and Sharp DTI and I ordered a little device called a “Nano Tram”, I’ll see how well it does for quick column squaring. When tramming there is NO such thing as “good enough”. Even a hair’s width error across the full travel in any direction… well, let’s just say spend the time, get it exact. I used to think a thousandth was precise and accurate – HA!


A rotary table is a worthwhile addition. A lathe chuck mounted to the rotary table (vertically) is not so great. Turning a piece stock using the end of an end-mill produces poor results. It will nicely cut a groove (the width of the end-mill) around the circumference of the stock, or put a nice flat along the length of the stock, or make it easy to cut a feature in the center of the stock or at various angles and degrees of rotation, but that’s about it.


Seems proficiency in machining comprises two elements – how to use the equipment (to execute the work) and conceptualizing the solution – how you approach the solution (set-up the work) for the best outcome (some methods skin a cat better).

Work as many projects simultaneously as possible. There are efficiencies to be had and the possibility of minimizing tooling and work holding changes.


I want straight edges and flat surfaces! While my little mill will cut anything I can fit on it, the main limitation seems to repeatable high-precision work (again, this is a beginner’s experience).


Other:
If you want to cut larger non-ferrous stock on a table saw do it outside and when there is NO WIND. I felt like I was inside a snow globe. The maelstrom of tiny aluminum flakes are almost weightless, very widespread and get into every orifice including the operator's - what a freaking mess! I mentioned wind, I set-up in corner of the building right where the air currents made large vortices. I really wish I had a video of that scene – indescribable.

greystone
12-01-2015, 05:08 AM
Me too.
15.000 work hours, and 100.000€ later, I am approaching the goal.

Excellent post.



I want straight edges and flat surfaces!
While my little mill will cut anything I can fit on it, the main limitation seems to repeatable high-precision work (again, this is a beginner’s experience).

JohnAlex141r
12-01-2015, 08:11 AM
Thanks for the reference for the air pump - I found the one I have very noisy. I do keep a drinking straw nearby and blow the chips away with that when I'm doing something small/quick when I don't want the noise, but have been looking for something small and quiet.

John.

RB211
12-01-2015, 10:59 PM
A larger mill, even one that is some what clapped out, will be more accurate for the fact you can mount glass scales and a DRO to it. My Bridgeport is somewhat clapped out, and if I had to go by the dials alone, I would pull my hair out. The DRO allows you to see how the tables move and handle backlash, including using the table locks, and the movement they introduce! The movement can be almost .001 at times.