Filling my milling machine with epoxy sand to increase rigidity.

[@RobertAdairWorkshop]

This made such a difference on the usability of the mill. If you are considering it, do it. You’ll be amazed by how much it improves overall machine performance.

[@Michel-Uphoff]

Robert, very well executed modifications. And you where right to use sand as filler. I expect you will benefit from strengthening the base. Given the low Young's Modulus of the epoxy concrete, the reinforcement of the column will be limited (possibly less resonance in some operations). I don't know the dimensions, but if I have to roughly estimate, the column is 80 cm high and about 12 cm in diameter with a wall thickness of 12 mm. If I calculate the deflection with and without the epoxy filling, the increase in rigidity for the column alone is of the order of 40%. Actually I am quite interested in the results of your measurements. I measured the increase in rigidity of my milling machine in a number of ways and made a video about it. Maybe my measurements/approach will be useful to you.

[@Ben.last.name.]

First off, great work doing such a clean job and pulling off the protection of the leadscrew and clearance holes so effectively! And thank you very much for your thorough explanation of the ratio of aggregate to expoxy used, and the methods used to get a consistent mix and control the mess while filling your machine. Don't be too quick to throw the idea out due to the "low density" of your mix! Adding overall mass by filling hobby machines helps reduce vibration, but it doesn't represent a large percentage of the weight of the assembly no matter the fill material, short of using lead or tungsten carbide maybe 🙃 The real win is the damping effect of the fill material, which will be significant in your case, but as another commenter posted, the fill is often comprised of multiple sizes of aggregate/mix-ins that include sand + pea stone, chip or clear crush gravel, and more oddball materials that are thought to improve the bandwidth of damping effect, including materials such as chopped fiber, screws, lead shot, scrap bolts and nuts, ham sandwiches, and stickers.. The idea behind the fill being made up of a wide range of densities and aggregate shapes is that each size and type of material will deaden different bandwidths of resonant frequency. Using a non homogenous mixture with randomly oriented materials also helps with arresting the transmission of vibrations from one end to the other of the column or base casting. Despite using just sand and epoxy in this case, which is far easier to mix, I think you will be surprised by the overall results! You have almost certainly increased the rigidity a very noticeable amount, in the column, but more so in the casting where the column bolts to which is often a weak point in bench mill designs. I'm curious if adjusting the tension in the all-thread will provide the ability to tune out resonance at a particular frequency, perhaps improving your most common tooling setups. Please make a follow up video as the community of hobbiests that are interested in expoxy fills is massive and we always are excited for another example/method to learn from! As a final note, you can significantly improve the regidity of the machine between the table and bed with a strong arm that can go from the table framing up the behind the column and be fastened to the column cap l, or top end of the all-thread you installed. Of course will need to be installed with clearance between the column and strong arm to allow the mill head to move freely about, and it will restrict the use of the mill for the rearmost 20-30* of rotation that you might use to do basic drilling of tall parts sitting on the floor behind the mill, if you don't have a floor standing drill press.

[@RobertAdairWorkshop]

I really appreciate the information. It's actually inspired me to do the head as well. I'm working on that today. I'll include it in the next video. I'm going to take your advice on the fill material.

[@edkcustoms]

WOw! i want to try that one my cnc machine, Throw some gravel in with the sand and epoxy to. Not sure how to calculate the mixture though 😂

[@misterfixit1952]

It's good to see someone still doing upgrades to the venerable but much maligned round column mill/drill. After owning mine for 15 years, I still love it and have finally started my own upgrades starting with a DRO with glass scales and a power feed on the x axis. Also in the works is a square column retrofit using linear rails and a square steel tube that exactly fits down over the round column giving me the ability to swivel the column but still be able to do precision head lifts. I'm looking forward to more of your videos regarding your round column mill/drill. Hopefully I will post some of my own, soon.

[@agentcovert]

Typically there's more then just one type of sand in " epoxy granite " such as pea gravel and a 2nd type / size of sand too..regardless it's also about flex and overall mass besides the damping..those cast iron castings will be much stiffer now..and adding mass to Chinesium equipment is a good thing..

[@nbprotocol5406]

It's not only the stiffness it's also the ability of the material used to disapate vibration.

[@bartoszskowronski]

I think loose sand (or lead shots) in the column would have even better result. Because under vibration loose grains will move and dissipate energy. (like in dead-blow hammers)

[@fredbecker607]

Pam cooking spray is a good release agent for epoxy. We used it for rifle barrel bedding.

[@RobertAdairWorkshop]

That's really good to know.

[@fna-wrightengineering]

Definitely interested in the results! I doubt it was a waste of time... Every little bit helps. I've thought about doing this same thing in my mini mill, which is way more of a wet noodle than your round-column machine. I've also looked into a product called Hard Blok, which is an engine block stiffener used by drag racers. It seems to basically be cast iron particles (the manufacturer calls it "graded cast iron") in epoxy. It's probably a bit more expensive than your method, however.

[@jamesolivier3192]

I bet lead shot and epoxy would be equal or greater density. Ive also got a round column. curious if this makes a noticable improvement.

[@ronwalsh]

Looks like a sound idea to me. I wonder if concrete would be heavier than the sand. I have a new drill press that I have considered weighing down, and this seems like a good idea.

[@Ben.last.name.]

Concrete makes a poor choice for fill material as it invariable shrinks while curing and therefore doesn't maintain contact with the inside of columns and castings as well as epoxy or non-shrink grouts. It also readily transmits vibrations and ringing and is a very poor damper.

[@blohnot]

Hi Rob, Great project, will do the same! Look forward to seeing your next video 👻🙏👌💪

[@criggie]

When doing your testing, consider the effect of the table. Yours looks pretty beefy so that helps, but as a variable consider bolting the mill straight to the concrete as a test. I know my tools resonate sometimes on a fairly flimsy table.

[@zimmymczimmerman8276]

So 😅 I may be becoming a pest but I stumbled on your video as I came across a JMD-18 that I’ll pick up. Do you have a teardown video of the jet drill/mill?

[@RobertAdairWorkshop]

Sadly, no. I didn't think anyone would find it interesting and I'm was eager to get it restored so I didn't film it. The hardest part is getting the pulley off. Use a puller and tighten it down just a little bit. Don't use the puller to actually pull the pulley, just give it some upward force. Then take a torch and heat the pulley up. Once hot enough, it'll pop off. I broke mine trying to remove it and had to turn it down on the lathe.

[@zimmymczimmerman8276]

@ so I watched a few videos and armed with my degree from the University of KZbin I managed to tear it down and move it. Conceptually the disassembly is similar to a drill press albeit on a larger and much much heavier scale. Only real stumbling point was removing the x-axis lead screw; needed to remove a pin (on one side) that goes straight through the lead screw. My next questions will show how green I am: 1) what did you use to remove all of the grunge and 2) what do you recommend to lube the lead screws, spindle and another moving parts that are inaccessible when assembled?

[@philt214]

Some years ago I must have read something about stiffening my HF round column mill/drill by attaching a bracket to the top of the column and then using a 3 point attachment to the wooden joists in the ceiling. I also had the mill bolted to the metal stand I purchased and I bolted the stand to a concrete pad. It did make things stiffer, however I had no real way of measuring how much. It will be interesting to see what your results are. How will you measure the difference?

[@RobertAdairWorkshop]

I attached a rope to the spindle, used a lever to make it parallel to the table, and hung a weight on the end of the rope. That gives me a known force on the spindle. Then measure deflection at the end of a 1/2" end mill. I'll have to be careful when doing it for the epoxied mill so they are the same setup.

[@Koptokaf]

Oh my! What is that absolutely delectable looking lathe behind you in the explanation part of the video? Cream on chrome Art Deco sweetheart!

[@RobertAdairWorkshop]

It's a little 6" Craftsman 109 lathe. Also made by Dunlap. It's an upcoming restoration project that I'm really excited about.

[@Koptokaf]

@@RobertAdairWorkshop Excitement transferred :)

[@rogermccaslin5963]

I'm fairly new to this so excuse my ignorance but I have a few questions. Sand isn't the densest material out there. Talc is more dense (about 60% more), mixes readily with epoxy, and doesn't cost much. Ever try that? Even better, has anyone ever considered steel or lead shot mixed with epoxy to do this? I'd imagine, with steel or lead, you wouldn't need as much epoxy. You would just need enough to wet the shot and act as a glue rather than a void filler. The shot cost could be offset some by the lower glue requirements. Is filling the cavity, edge to edge, so to speak, an important factor or could you just cast lead ingots of appropriate sizes and glue them in instead of trying to fill the void fully?

[@RobertAdairWorkshop]

Sand isn't the ideal choice, I think. I used it because it was cheap and easy to get. I will say there was a vast improvement in the mill's performance after doing this. I am using the same process on another machine I'm building, but on that one, instead of sand, I'm going to try a product called Amasteel. It's a steel-based blasting media with a density of about 450 lb/ft3. I think completely filling the voids is better from a rigidity standpoint. It adds a shape to the inside of the mill which provides additional resistance to deflection. I'm wondering if a combination of the two might work. Cast iron ingots mixed in with a media and epoxy to get both a density increase and a rigidity increase.

[@rogermccaslin5963]

@@RobertAdairWorkshop I see. I wasn't thinking about the rigidity added by filling the cavity. I suppose it's akin to the torsional difference between box tubing and a C channel. Your answer was very helpful. Thanks. I've been thinking of buying a mini mill for hobbyist projects so I've been watching a bunch of videos on the subject. Most of the complaints, tweaks, and improvements seem to fall into two categories, either stiffness/vibration issues or lack of power. I look at the lack of power is a matter of patience. The machine is only going to do what it can do. Don't expect to plow a 1/2" endmill full cut through steel on a benchtop mill. The stiffness and vibration seems to be a matter that can be improved with a minimal amount of heartburn. I'm not shipping parts to NASA. I just want a machine that will move some metal out of the way now and again. If I could get to a few hundredths, that would be fine for 95% of my projects. Hell, to be honest, most of them would work at a tenth.

[@RobertAdairWorkshop]

@@rogermccaslin5963 I have a Jet JMD15. It's the same as many of the Rong Fu round column mills. I like it, honestly. I found this one or $1k on Craigslist. It's a '99 model and needed a full reconditioning, but for that price, it included collets, clamps and some tooling. I might be biased, but I think these are a better mill than the 'mini' mills you see online. The machinist guys don't like round column mills, but for the rest of us, they seem to be a good solution. Might be something to keep an eye out for.

[@rogermccaslin5963]

@@RobertAdairWorkshop Thanks. I will do that.

[@shalehausler4383]

I would think you will get good vibration damping.

[@cecilomar]

At 01:35 I thought: "Man, I hope this guy has a 3D printer. It would be such a simple solution.".

[@RobertAdairWorkshop]

Ha!

[@thomasking2081]

GREAT VIDEO ROB, I WAS GOING TO DO THE SAME THING TO MY DRILLPRESS, BUT I WAS GOING TO USE HIGH STRENGHT CONCRETE

[@Ben.last.name.]

@thomasking2081 People often think of conrete as a good choice but in reality almost all varieties of concrete mix shrink while they cure and do not do a good job of maintaining contact with the inside of castings or columns. This greatly reduced the damping effect, and they're also corrosive while wet/humid and tend to absorb atmospheric moisture and contribute to rust! Loose sand can be a great material to fill the column with short of spending $$$ and effort on epoxy.

[@Michel-Uphoff]

I would not do that. Cement concrete shrinks and does not adhere to steel. You are left with a column or bed containing a rattling stone that does nothing.

[@sacriptex5870]

maybe iron fillings with epoxy