Dewalt chop saw fault

[plewlandsbob]

Got a problem, with this chop saw, it starts to run up, then gets up a little bit of speed, then it goes out with a flash and a bang. The brushes, were replaced , when the fault first appeared, since they were very worn.
Any ideas, what could be at fault, or if it is fixable?

 

[cheb]

Clean the bit the brushes rub against, the name of which won't come to my mind. Also clean out the grooves in the same bit, I use a dental pick. It might not cure but it probably won't hurt.

 

[brightspark]

armature looks burnt .some windings down. i bet it sparks like mad

 

[zzr1200]

Commutator could do with a skim/clean and new bushes, but that may not fix it.

The motor has probably eaten to much abrasive disc and metal dust, possibly time to invest in a new one........

 

[brightspark]

once they are burnt the segments come loose and a skim doesnt work its knacked apart from buying a new armature . is it worth it depending on price

 

[zzr1200]

is it worth it depending on price

Sorry B/S, mis-understanding the armature should be binned along with the rest of the saw, time for a new saw......

The OP could still try a skim, he may get lucky.......

 

[plewlandsbob]

I won't bother trying , to repair it. I took it home from work, before it landed in skip, as we got a new one, after trying a set of brushes.
It is 23 years old. Boss bought it and a ,Thermal arc 360, mig welder, when he started out, on his own. Transformer went on welder last year.

 

[zzr1200]

I won't bother trying , to repair it. I took it home from work, before it landed in skip, as we got a new one, after trying a set of brushes.
It is 23 years old. Boss bought it and a ,Thermal arc 360, mig welder, when he started out, on his own. Transformer went on welder last year.

It's earnt it's money.

 

[bourbon]

time to retire it.

 

[Agroshield]

All the parts suppliers show the armature as discontinued. This one lists a price (not sure if it is the 110v or 230v) but even if available at that price (£90+), it is not economic.

DW871 Type 1 Spares and Parts for DeWalt DW871 (Saws) - Power Tool Spares

www.powertoolspares.com

 

[sardine]

You can replace just the commutator , but it's a motherload of a skilled job, cut the old one out on a lathe and bring all the connections out , I would have a go if I had the time or need. A new commutator is only 6 quid.

 

[Chippie]

You can replace just the commutator , but it's a motherload of a skilled job, cut the old one out on a lathe and bring all the connections out , I would have a go if I had the time or need. A new commutator is only 6 quid.

Before doing that, you need to check the armature slot relationship with the comm bar-slot positioning.....otherwise you could end up half a comm bar out...it would spark nicely...
I have rewound armatures before...

 

[Screwdriver]

If you can be bothered to wrap it up, I'd buy that for the cost of postage.

Nice solid bit of kit, also worth breaking for parts if it can't be fixed.

Serious offer if it's not too late.

 

[Agroshield]

I would first compare the quality of the old machine versus a new replacement.

Please, what was the result of the comparison that you did? I could not see any numbers in your post.

It is going to be difficult to find a place that actually had the armature in stock, available for delivery. Every other place I looked, the part is noted as discontinued. The one place I showed above it is more likely that they have forgotten to update the page rather than the part being available.

I did go and have a look and found this one: https://www.ebay.co.uk/itm/313698308838 £217.54 and if you buy before 6 June, there is another 10% off, making £195.79

 

[Chippie]

Please, what was the result of the comparison that you did? I could not see any numbers in your post.

It is going to be difficult to find a place that actually had the armature in stock, available for delivery. Every other place I looked, the part is noted as discontinued. The one place I showed above it is more likely that they have forgotten to update the page rather than the part being available.

I did go and have a look and found this one: https://www.ebay.co.uk/itm/313698308838 £217.54 and if you buy before 6 June, there is another 10% off, making £195.79

Jeez..thats dear...expensive...Wouldnt even cost a fraction of that for the copper to rewind it...( well not even 25%.... ) Assuming you had the tech know-how to strip and rewind it...