DA Sander Repair

Reply

  #1  
Old 02-18-15, 01:05 PM
W
Member
Thread Starter
Join Date: Apr 2003
Location: Ohio
Posts: 1,930
Received 16 Votes on 15 Posts
DA Sander Repair

I have a National Detroit DA Sander that has not operated for a year. (press the air trigger and nothing happens. I can hear some air releasing somethere but not sure where. I took it apart to see if there are any O rings in it, and there are a couple on a small pin, but the dealer I bought it from said they can't get them and that sending it back to National Detroit would not be cost effective for me. Before I try to match O rings myself, I thought I would put this out there to you guys to see if I am on the right track. It is model Z28247 (EZQ) Any advice is always appreciated!

WML13
 
  #2  
Old 02-18-15, 01:20 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,495
Received 36 Votes on 28 Posts
Is this your sander? http://nationaldetroit.net/partspdf/Model%20EZQ.pdf

Read the servicing instructions and if you have any questions I would either call then or send them an E-mail.

If you were not diligent in using the proper lubrication then it may be that the vanes of the air motor are stuck in the slots. A thorough disassembly and cleaning may be necessary.
 
  #3  
Old 02-18-15, 04:55 PM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Location: USA
Posts: 26,588
Received 791 Votes on 728 Posts
Most air tool problems can be fixed as Furd said, by disassembly, cleaning and lubrication. I've talked to guys in repair shops and they say that 90% of the time that is all they do... they don't even have to replace any O-rings or parts.

Obviously sometimes things break, but you ain't out anything but your time if you take it apart, soak it, and clean it. Lube it lightly upon reassembly. Nothing should be dry.
 
  #4  
Old 02-18-15, 07:29 PM
W
Member
Thread Starter
Join Date: Apr 2003
Location: Ohio
Posts: 1,930
Received 16 Votes on 15 Posts
DA Sander Repair

The diagram you sent is correct. It seems to be straightforward as far as the disassembly process, so here we go, another skill to learn before I kick the bucket!

Thanks for the replies!

WML 13
 
  #5  
Old 02-22-15, 02:41 PM
W
Member
Thread Starter
Join Date: Apr 2003
Location: Ohio
Posts: 1,930
Received 16 Votes on 15 Posts
DA Sander Repair

Sorry to be a pest but the instructions were not as straightforward as I thought. It describes removing the head assembly, which I did, WITHOUT removing the bearing and shaft assembly. (yet) As I read down further, it appears that Disassembling the air motor is a separate procedure from removing the motor shaft. It appears to me that they want you to tap on the end of the rotor shaft with a soft nosed hammer to dislodge the upper and lower Motor Bearing Plates. In my opinion, that would be difficult to do if the shaft is removed first, unless I am missing something. If I do the hammer thing, it appears that THEN I can remove the rotor blades WITHOUT removing the rotor shaft from its bearings and do the cleanup right there. Does that make sense?
 
  #6  
Old 02-22-15, 04:10 PM
GregH's Avatar
Super Moderator
Join Date: Jan 2001
Location: Manitoba
Posts: 10,165
Received 44 Votes on 42 Posts
If you haven't taken too much apart a quick way to try to revive your sander is to flush it out with WD-40.
This is what WD is good at.......it is more of a cleaner than a lubricant and if yours is gummed up it may makes things move.

Just take a can with a straw on the end and insert it in the air fitting.
Press the go lever and spray a good volume into the tool, let it sit for a while, hook up the air line and see what happens.

Make sure you cover the exhaust with a rag.
 
  #7  
Old 02-22-15, 05:40 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,495
Received 36 Votes on 28 Posts
I would not advise using WD-40 UNLESS you immediately follow up with some solvent and the proper air tool oil. WD-40 used in air tools has a tendency to leave a gummy substance after the carrier evaporates. I have seen air tools totally seize up when WD-40 was used.

A little deodorized mineral spirits with about 25% (by volume) air tool oil mixed and use a syringe to inject it in to the air inlet fitting. Run the tool in short bursts with a rag over the exhaust as Greg recommended. Do this several times and then use just the air tool oil adding enough to get an oily mist out the exhaust.
 
  #8  
Old 02-22-15, 06:34 PM
W
Member
Thread Starter
Join Date: Apr 2003
Location: Ohio
Posts: 1,930
Received 16 Votes on 15 Posts
DA Sander Repair

So you want me to still use the WD 40 as a cleaning agent first? Or just use your recipe to do it all? The motor will not rotate at all right now.

Thanks for the help!

WML13
 
  #9  
Old 02-22-15, 06:40 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,495
Received 36 Votes on 28 Posts
If it won't rotate at all you have no choice but to completely disassemble it.

I personally would not use WD-40 at all but once completely disassembled use the mineral spirits and oil.
 
  #10  
Old 02-23-15, 07:24 AM
M
Member
Join Date: Oct 2003
Location: PA, USA
Posts: 748
Received 0 Votes on 0 Posts
I second Furd here - if it does not rotate it has to come apart.. Maybe the rotor dug into one of the endplates and is stuck or the bearings are shot. Either way you'll have a bit of a project here. The bearings will need to be cleaned and inspected, and possibly replaced. Endplates will have to be lapped flat, vanes inspected for damage and also possibly replaced. Then the whole thing has to be assembled with very tight tolerance, using shims. I hope you have a small arbor press and can fab up some quick fixtures.
 
  #11  
Old 02-23-15, 10:06 AM
W
Member
Thread Starter
Join Date: Apr 2003
Location: Ohio
Posts: 1,930
Received 16 Votes on 15 Posts
DA Sander Repair

I have to apologize, the motor shaft will turn if I turn it from the outside manually. It just won't turn under its own power when I hit the trigger. It will spin quite easily using my fingers. I have the mineral spirits and the air tool oil ready to mix on the bench. I will try it.

thanks!

WML 13
 
  #12  
Old 02-23-15, 10:44 AM
M
Member
Join Date: Oct 2003
Location: PA, USA
Posts: 748
Received 0 Votes on 0 Posts
No problem

You're in good shape then. Keep in mind that the cylinder is drilled lengthwise to make air enter the motor on both sides at the same time. Carefully poke in there with a toothpick or plastic tube brush. It gets gummed up or rusted over sometimes. Good luck.
 
  #13  
Old 02-23-15, 12:41 PM
W
Member
Thread Starter
Join Date: Apr 2003
Location: Ohio
Posts: 1,930
Received 16 Votes on 15 Posts
DA Sander Repair

On my way!

Thanks again!
 
  #14  
Old 02-23-15, 06:12 PM
W
Member
Thread Starter
Join Date: Apr 2003
Location: Ohio
Posts: 1,930
Received 16 Votes on 15 Posts
DA Sander Repair

High fives go all the way around! After soaking it with your recipe, I just nudged the trigger a few times while turning the rotor shaft manually and it let loose like a scalded dog! I continued with by injecting straight air tool oil and am leaving it set to soak some more before I put it all back together.

Thanks again for the great advice!

WML13
 
  #15  
Old 02-24-15, 12:47 AM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,495
Received 36 Votes on 28 Posts
Glad you got it working. In the future add a few drops of the air tool oil into the air inlet each time you use the sander. If you use it for several hours a day add a few drops every couple of hours as well. Use a rag over the exhaust and run it no-load for several seconds to expel any excess oil before using it on any surface that can't take an oily mist.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: