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More torque

Hukshawn

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#1
The mini mill. Is there a reasonable way to squeeze more torque out of the stock parts?
It over loads when drilling holes. Even smaller holes.
 

RJSakowski

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#2
1. Bigger motor
2. Gear (pulley) it down
Torque = power/rpm
 

RJSakowski

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#3
If you are using a VFD, slowing down the motor is usually ineffective. My Tormach has a 3 phase VFD and is fairly well useless at the lowest speed setting. Using a set of speed reducing pulleys or gears will lower the rpm but will increase the torque proportionally. Motors are usually rated for power at a fairly high speed. You can calculate the rated torque from the the formula torque (lb.ft.) = hp x 5252/rpm. Torque generally does not increase much as you lower the VFD speed.
 

Hukshawn

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#4
So the short answer is no.

I don't have the greatest drill bits ever made, I was drilling a hole for a 1/4-20, and in the 1" of drilling I had to reset the motor 3 times...
 

tq60

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#5
No..

Reasonable way to increase the usefulness of the machine is to properly use it within its limits.

Adding a larger motor or altering existing one will create a weaker point somewhere else that may not stall but break.

If stalling drilling holes then check your tools for being fit to work then use only enough pressure or rate of feed to stay within the limits of said tool.

Here the line " let the tool do the work" applies.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk
 

Doubleeboy

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#6
Your mill is not capable of drilling a 1" diameter hole in hard materials. If you insist on drilling large diameter holes, get good drill bits, with split point and web thinned. There are youtube videos on how to thin a web and grind split points. I would think if would be easier to start the hole with small drill, step up in size until you can use boring head and bore the hole to correct diameter. I bet the manual of your mill states largest drill size and I am sure 1" is way beyond its capabilities.
 

Hukshawn

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#7
It wasn't a 1" hole. It was a .260" hole to a depth of 1".

But I'm getting the general consensus here.
Thanks guys.
 

higgite

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#9
Shawn,

Are you clearing chips out the hole frequently? If not, they could be binding the bit in the hole, or trying to, and overloading the motor in the process.

Tom
 

Hukshawn

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#10
That had been the problem once it twice but not always. I may just not be fully aware of the limits of this little machine. Also, i was using the machine for a few hours by that point. The overload circuit might have been weak due to heat. I notice the control box on the back does get warm after heavy usage. I have a small 12v fan I plan on putting in there. I recently bought a 12v gear motor and DC controller to build a power feed. I was planning on putting the controller in the box and knew I'd definitely need a fan to keep things cool.
 

brino

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#14
Is there a reasonable way to squeeze more torque out of the stock parts?
So the short answer is no.
Hi Shawn I just read the entire thread and came to a much different conclusion.

To me it sounds like a number of very reasonable ideas and the first few I'd consider "low hanging fruit"; stuff that's just worth doing for every machine just to add longevity.

1) use sharp tools,
2) check the power to the machine to make sure it's not getting "choked" by long runs and wrong gauge wire,
3) change the pulleys/belts to up the torque if you can sacrifice the RPMs
4) upgrade the motor

I would also add: mind your speed, use cutting fluid when appropriate, lock any gibs not required for this cut.
Try to stack every little detail in your favour, especially with smaller machines.

More info on the machine would also help folks with a similar unit compare results.
What make and model of mill, what HP motor? What tool and what material?

-brino
 

royesses

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#15
There are guys installing motors and controllers from used tread mills. Do an internet search if you are interested. They are a lot more powerful but then another weak point may show its ugly head. I've drilled up to 1 1/16" holes in aluminum and cast iron with my mini mill using Silver And Deming drill bits. It takes time to step up to the large drills. I keep my drills sharp and have not had a problem stalling the mill. Sharp drill bit, good cutting oil and drilling the large holes >1/2" in steps works for me. You give up speed and convenience with the small machines unfortunately. Check your brushes for defects also. I've seen some brushes that weren't radiused to fit the armature cause low torque.

Roy
 

Hukshawn

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#16
It's the busy bee cx605. Same as the harbour freight mini mill, or x2 mini mill. I believe it's 300 watts. Stock motor. The bit wasn't in the greatest of shape, the machine had been used for several hours, so maybe overheating overload circuits. It was in low gear. Electrical feeds are not the issue. If anything at all in that area is the electrical cord provided with the mill. Could be a higher awg.
All in all, I think I was just surprised how quickly the controllers overload kicks out. I realize it's not anything close to a medium duty mill, and shouldn't expect anything close to the power... I'm still learning about this machine. Understanding it's limitations.
I suppose I was looking for someone with some kind of info on whether or not there is a potentiometer on the controller that could adjust the overload kick out. But maybe it's better I don't modify it...

I think I'll add the power feed to this machine and probably stop there, as far as upgrades go. It's clear I need a bigger machine for my expectations. I don't care for limitations. I don't like being held back by something. I want a machine that will do whatever task I need of it. But this was what needed to happen. If I started with a powerful machine, who knows, maybe I'd chop my arm off cause I didn't understand it's capabilities or respect it's power...
Besides, I really need to save up some money now and buy a proper mill vise. This drill press vise is awful. It's crooked 6 ways from Sunday! And constantly rigging up the clamping set is time consuming.
 

brino

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#17
Hey Shawn,

The page at: http://www.busybeetools.com/products/milling-machine-mini-craftex-csa-cx605.html
states:
It features a 1/2 HP motor and has a maximum milling capacity of 5/8" and drilling capacity of 1/2".

I'd expect a little more than what you're seeing from a 1/2hp motor.

My little Jobmate 55-5901-6 drill press has only a 1/4hp, 2.4A motor and I would expect it to drill 1/4" holes in steel.
(I'll try to test it for sure tomorrow)
I'd want to run that drill about 1200 rpm, but given the pulley steps I have choices between 1100 and 1450 rpm.
The lower rpm should give slightly higher torque.

-brino
 

FOMOGO

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#18
Sharp bits for sure, but as Tim the tool man always said, you can never go wrong with " MORE POWER ". I know, but what could possibly go wrong. Seriously though, sometimes too little power, is more problematic than too much. Mike
 

Chipper5783

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#19
Also highly likely...
that the drill is dull.

Have you looked at the two support lands just down from the cutting lips? When someone pushes a dull drill bit, it breaks down the support lands - that leading edge will be smaller than the lands further up the drill bit. When the bit is resharpened, it will start cutting fine, but it is cutting a bit undersize. Then when the full size portion of the drill enters the hole, it will bind resulting in poor performance of the drill bit, lots of heat and require lots of torque (further damaging the drill bit). The remedy is to cut the drill back to where it is full size and repoint the drill. Of course a better solution is to stop drilling when the drill bit starts to dull and resharpen - then just a quick touch up and you are ready to go again.
 

JimDawson

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#20
The other question that has not been asked is: Is it wired for the correct voltage? Maybe wired for 230v and running on 115v?
 

Tozguy

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#21
If the mill had been operating for a few hours without problem and then started to trip, as you wrote heat build up in the motor is the likely cause. Hobby machines are not usually rated for continuous duty.
 

MozamPete

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#22
The overload could also be faulty and tripping prematurely (I have seen this happen with MCBs operating under there stated rating).
 

Silverbullet

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#23
There's one other cause or two. The drill bit is poor quality and breaking down causing the material to work harden , or the material itself is hard or case hardened . I've seen guys weld drill bits in holes trying to push thru. If the drill bits not cutting chips it's not cutting at all. The more pressure will not make it cut. Most run drills to fast for the material being cut. Drill presses are almost always way to fast even at the lowest speed. My guess his bit wasn't sharp or it is cheap China junk. Just my thoughts.
 

ch2co

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#25
Here's a shot of my little stock Grizzly minimill drilling a 1" dia. hole in two cast iron weights. I started with 5/8" pilot hole.
Couldn't believe how easy it was. The mill just purred away. The drill was sharp. I've never experienced an overload kickout off the power supply.
This was a used machine to start with, otherwise it is stock, no new motors or controllers.
SHARP TOOLS!
IMG_2608.jpg
 

clevinski

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#26
I have a Real Bull mini-mill that I converted to belt drive (which had the unfortunate, undesired side-effect of actually LOWERING the torque), and I have no trouble drilling deep 1/4 inch holes in mild steel. I keep my bits sharp (at the risk of starting a debate, thank you, Drill Doctor!), and clear the chips from the hole every so often. I use cutting fluid while drilling (I use Re-Li-On for this). I have cut 1/2 inch holes, though I definitely step up to this size, probably drilling 3/8 inch before drilling the 1/2 inch. I think there have been a number of excellent suggestions above and won't repeat them here. The one that I will add is that a boring head would be a useful way to make larger holes with minimum machine load, though the increased number of passes needed means it will take longer. Good luck, and let us know how you make out!
 

Bi11Hudson

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#27
I have a small machine similar to that. Originally for drilling the edge of thin plexiglas but now as a general purpose drill press. It came with a 1/2" chuck and has been used for a 7/16" drill, in mild steel. I have had trouble with the speed regulation circuit board. A component was out of tolerance. I repaired it myself, that's my real job.

It sounds here that if your drill is sharp, even moderately dull, it should at least squeal if the metal is too hard. If that hard, I wouldn't try a HSS tap in it. I know what happens there. That has arisen also, but years ago. I didn't draw a temper enough. Know better now, but when you're new...

Maybe it'll help. Those circuits are Chinese and if the magic smoke ever gets out, it will drive you nuts trying to figure out how to get it back in. Good luck with it... Bill (Old Man) Hudson
 

brino

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#28
Shawn,

I finally got back to testing my little 1/4hp drill press. This little drill press usually lives at my electronics bench in the basement, but I took it to the shop to help contain the swarf.

label.jpg


press.jpg


I used a decent (not perfect) 1/4" drill bit at 1100rpm. No cutting fluid. No centre hole. Drilling thru a 1" piece of mild steel.
The camera (phone) was propped up on a cardboard box on the bench between me and the drill press, so please forgive the extra movement....

Attached is a video. As you can see chip ejection was good, but I did manage to stall the motor(twice) when the bit broke-thru of the backside.

Just meant as a comparison to your results.

-brino

EDIT: I guess the video didn't make the first cut....I thought I had uploaded it, so I must not have "inserted" it....or something......let's try again......Nope, maybe it's too big!

Oh well, nothing earth shattering anyway. I drilled a 1/4" hole thru a piece of 1" steel on a small crappy and loud drill press.
 
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bobshobby

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#29
To start with HP = torque x RPM. or HP/RPM=torque. Bottom line halve the speed =double the torque. Do not use electronic speed control to lower speed it will also lower torque, change some belts or gears. gear boxes are known as torque multipliers for this reason.

Do not be afraid to run well below recommended cutting speed with HSS. HSS is very forgiving whereas carbide is not.

Check your motor is actually running at it's rated power.

Be wary of putting a more powerful motor on your machine. certainly not more than 1&1/2 times original power, should be a maximum. You might break something

Ensure your tools are sharp, really sharp. If you are not an expert , I mean "toolmaker expert" at sharpening drills , get yourself a drill doctor. HSS will always require less torque than carbides for the same job.

Use pilot holes when drilling. especially in hard materials. consider boring larger holes, on your small machine probably anything over 3/8 inch, certainly over 1/2 inch in mild steel