help diagnose a weak cordless impact

[rust in the eye]

I have an 18v Milwaukee 1/2" cordless impact(9079-20) that has never been satisfactory.
Milwaukee exchanged the batteries when it was new as it had been on the shelf a long time before my purchase. The fresh batteries improved it some but it never seemed very powerful so it fell into disuse until recently.
Having bought fresh batteries I expected to press it back into service but it is weak as a kitten.
Taking it apart I see the field magnet is cracked so I order a new one and install but no change. I've checked the armature for shorts/open windings, it checks good. Brushes are very good, commutator has been cleaned and shows almost no wear. Planetary gears are all free and lubricated, bearings are smooth.
I have tried several new batteries, a know good charger (in case mine had gone kaput) and switch operates fine, no heat to indicate poor contact.
Scratching my head here wondering why this thing is such a wuss.
ideas?

 

[Kaizen]

What are you comparing it to? Maybe it is what it is. Have you looked at the specs on it?

 

[matt_i]

You should investigate whether it is under warranty. And if so I would send it in, its all free of charge. I think its 5 years, the unique serial number on the side will determine if you can process a warranty claim. I sent in an M18 drill that lost speed control and they replaced every part on the whole thing except the plastic clamshell. (IOW I had no issues with the chuck nor the 2 speed gearbox but they put new ones in it !?!)

If its out of warranty, I'd give up and get a new "bare tool" and keep the batteries for the next one. The ~$99 you'll be out for a new warrantied tool is pretty small to me when you look at the cost of filling the parts cannon.

 

[DFB]

I think it be out of warranty

Wow that's an old Ni-Cad to boot

240FTLBS 1400rpm

What AMp Hr batteries do you have...the 1.3's?

https://www.amazon.com/dp/B00005RUQK/?tag=atomicindus08-20

 

[Showkey]

18v Milwaukee 1/2" cordless impact(9079-20) Are $39.00 on eBay.........well past their prime even if it was new on the shelf.

 

[pmiranda]

NiCad doesn't have the juice to run a decent impact. I got lucky with my craftsman impact in that they released a LiIon version of the battery that worked in the same tool and it was overnight way better.

 

[rust in the eye]

I think it be out of warranty

Wow that's an old Ni-Cad to boot

240FTLBS 1400rpm

What AMp Hr batteries do you have...the 1.3's?

https://www.amazon.com/dp/B00005RUQK/?tag=atomicindus08-20

yeah, 13 years old.
240 ft lbs was optimistic, when new it could ,barely, remove cylinder head bolts.
The current, new Chinesium L ion batteries are supposedly 3.0 ah, originals were 2.4. Tried two different chargers as well.
With a large socket attached and full charge I can hold the socket in my hand, pull the trigger and it just jabbers away.
It's got very low time and I'd like to use it again. I know it's old technology, so am I. For it's time it was supposed to be a good tool.
A friend has the new 20v IR, all $450 worth, that thing is a monster but I can't afford it right now.
The anvil portion doesn't look worn, again really low time on it, and nothing is obviously broken.
Still baffled.

 

[BPJOOP93]

That tool wasn’t good when new. I had the saws all of the same era and it was JUNK from new on. Sent it back 3-4 times and Milwaukee finally kept it. No reimbursement. Last Milwaukee tool set I ever bought.

 

[rust in the eye]

That tool wasn’t good when new. I had the saws all of the same era and it was JUNK from new on. Sent it back 3-4 times and Milwaukee finally kept it. No reimbursement. Last Milwaukee tool set I ever bought.

agreed it was disappointing compared to claims but if, for not too much $ it could work properly again it would be useful for me to have.
Having invested already in the batteries and a field magnet I'm a bit "pregnant" with this thing.
Milw will overhaul it for $150, thanks.

 

[DFB]

Milw will overhaul it for $150, thanks.

Wow that's steep obviously could get a newer one for that money

How's the spring?

 

[rust in the eye]

Wow that's steep obviously could get a newer one for that money

How's the spring?

Steep, indeed. I, on my first attempt, was able to dismantle almost entirely and re-assemble the thing in a few minutes. $150 will buy a 1/2" impact but not a strong as this is supposed to be.
I don't know how to evaluate the spring but it cannot be compressed by hand.
One of the posts above gives the original specs and looking that over now it may be turning too slow. I'm going to try jumping the switch which I've thought good but perhaps isn't.
Next I'll try dismantling the assembly with the spring. All that stuff looks like new.

EDIT: I'm convinced that the problem is electrical, seems to turn way too slow. Jumping the switch is nigh on impossible, no room for jumpers in the case. Checking for continuity I get strange results, the + term on the battery side has continuity to BOTH outputs. Removing a heat sink(clue) I see a transistor and circuit board inside this "switch".
A new switch is on order, hope it works as I'm in almost as deep as a new one now.
Wish me luck. Will post results for future reference.

 

[nealric]

That tool wasn’t good when new. I had the saws all of the same era and it was JUNK from new on. Sent it back 3-4 times and Milwaukee finally kept it. No reimbursement. Last Milwaukee tool set I ever bought.

All cordless tools were junk before the modern Lithium batteries. Seems a silly reason to write off Milwaukee. The new M18 Fuel has around quintuple the torque of the tool being discussed.

 

[BPJOOP93]

All cordless tools were junk before the modern Lithium batteries. Seems a silly reason to write off Milwaukee. The new M18 Fuel has around quintuple the torque of the tool being discussed.

The reason I wrote off Milwaukee was the ****** way they dealt with the problem. I was selling their tools at the time. Don’t you think they maybe would have wanted a tool rep to be happy so I could sell them with a clear conscience?

 

[DFB]

An inexpensive digital non contact tachometer with a piece of reflective tape can easily read how fast its turning. Thinking it be a difficult to know what the actual speed be otherwise

IMO 1400 max is pretty slow compared to the peak 2400 rpm or so of most newer ones.

$20-$30 from Amazon for something that

Hoping you can figure it out


As for pricing on a new impact wrench my 2861 Mid Torque -21 CT kit was only $199 at the time, granted the current XC kits are going for more money now

 

[kctyphoon]

I am pretty sure your impacts output - when new, with a fully charged battery, was about the same as their modern 12v today.. that might be youre problem.

Its big - cause its old.. that doesn’t mean its gonna compare to anything of today.

 

[rust in the eye]

Well, I promised to follow up.
The new switch, which I had high hopes would be the cure didn't do squat.
This tool is far weaker than when it was new. It's not the nature of the beast, something is wrong, I just haven't figured it out yet. It can't remove a freshly torqued (90#ft)lug nut.
The armature tests good, at least what I know to test, check for opens and shorts.
I'm going to bring it to the local tool store and see if they have any ideas.
Determined to make it work right.
has anyone here dismantled the impact mechanism on one of these? A pretty stout spring so I'm concerned with re-assembly.
Re NiCad v L-ion batteries: I agree the new batteries are better but I've had plenty of satisfactory tools that use NiCad.
The batteries I'm currently using for this tool are L-ion.

 

[ChrisLS8]

agreed it was disappointing compared to claims but if, for not too much $ it could work properly again it would be useful for me to have.
Having invested already in the batteries and a field magnet I'm a bit "pregnant" with this thing.
Milw will overhaul it for $150, thanks.

Why would you invest 200 into a paperweight? I know you seem to be stubborn however you might as well buy a Ryobi or Bauer impact for cheap and watch your "good for it's time" impact get blown out the water by bottom barrel guns

 

[rust in the eye]

Why would you invest 200 into a paperweight? I know you seem to be stubborn however you might as well buy a Ryobi or Bauer impact for cheap and watch your "good for it's time" impact get blown out the water by bottom barrel guns

Oh, I've done way dumber things with $200
I'm paying for my education in repairing power tools.
I already have another (Milwaukee) impact, this one is a back up.


So back OT, does anyone have experience dismantling the impacting mechanism?