PM 833-T Backlash

[Bill Kirkley]

Here is a link to the updated video which includes the fix. I deleted the old videos so those links won't work.

 

[Praeger]

I just discovered the same condition on my 833T. I took the same troubleshooting path (minus calling PM) and ended up removing the X-axis hand cranks, sliding the table to the left enough that that third bolt became accessible. It locked down in less than a full turn. Backlash down to .005". Exercise caution when moving the table so far as to get to this bolt - you'll be close to the tipping point for the table - it is heavy. I used an auxiliary out feed table to provide support.

As a PSA, anyone buying the 833T should check this during setup. Disappointing QC, happily an easy fix.

Bill - Did you disable the spring mechanism on the Y-axis hand crank? I find it annoying and used a zip tie to lock it in the engaged position. In your video it looked like you weren't pushing in the hand crank before turning it.

 

[Bill Kirkley]

Praeger- If you look at the thread "Shipping Dispute" you will find someone in the shipping department told me the spring handles are discontinued. They replaced mine with a real handle. If you contact them they should do the same for you. It seems no one liked the spring handle, including me.

Shipping Dispute

I ordered the PM-833T mill and power feed together. It came with two handle-dial assemblies and one spring loaded handle as part of the power feed kit. If I had ordered the two separately, I would have received three handle-dial assemblies and one spring handle. When I contacted shipping...

www.hobby-machinist.com

 

[mksj]

Are there any lock washers under those bolts, one would expect that they would loosen over time otherwise with the constant back and forth motion. Might also be some consideration to using some blue 242 Loctite.

 

[Bill Kirkley]

I don't think there are lock washers. There are a number of bolts on the machine that don't have them. I am not aware of loosening being a problem. I think this is an case of the bolts never being fully tightened.

 

[Praeger]

Praeger- If you look at the thread "Shipping Dispute" you will find someone in the shipping department told me the spring handles are discontinued. They replaced mine with a real handle. If you contact them they should do the same for you. It seems no one liked the spring handle, including me.

Shipping Dispute

I ordered the PM-833T mill and power feed together. It came with two handle-dial assemblies and one spring loaded handle as part of the power feed kit. If I had ordered the two separately, I would have received three handle-dial assemblies and one spring handle. When I contacted shipping...

www.hobby-machinist.com

Thanks - That's good to hear, I'll give them a call.

 

[Jason812]

I'm so glad you posted this thread. I too had .08" of backlash in the y-axis. The 6mm ratcheting wrench, 6mm cutoff cheap allen wrench, and screwdriver worked like a charm once I was able to get the allen in the bolt. I haven't touched the other bolts yet besides the 3rd screw and backlash is down to .013" and am afraid to tighten the bolt any more. I have .015" in the x-axis. Before I start trying to reach the other bolts and split screw adjustment bolt, what is the target amount of backlash?

 

[Bill Kirkley]

I don't know if there is an ideal target. I think it is what you can live with. A few thousands maybe. Some of the more experienced guys can probably give you a better idea.

 

[ahazi]

I just discovered the same condition on my 833T. I took the same troubleshooting path (minus calling PM) and ended up removing the X-axis hand cranks, sliding the table to the left enough that that third bolt became accessible. It locked down in less than a full turn. Backlash down to .005". Exercise caution when moving the table so far as to get to this bolt - you'll be close to the tipping point for the table - it is heavy. I used an auxiliary out feed table to provide support.

As a PSA, anyone buying the 833T should check this during setup. Disappointing QC, happily an easy fix.

Bill - Did you disable the spring mechanism on the Y-axis hand crank? I find it annoying and used a zip tie to lock it in the engaged position. In your video it looked like you weren't pushing in the hand crank before turning it.

I have the same problem on my PM833-T, about 0.055" backlash on the Y-axis, very low (less than 5 mil) backlash on the X-axis. I installed a power drive on the X-axis (on the left side).

Praeger and Bill not really clear how much disassembly of the table(s) you did? Can all this work get accomplished without removing anything and just squeezing modified allen wrench and turning the loose screws? When the X-axis table was released, did you have to take off both hand (left and right) cranks and the bearings that hold the lead screw?

I will take a closer look maybe stick in a flexible camera to get a better view. Annoying... I was expecting better QA.

Ariel

 

[davidpbest]

I have the same problem on my PM833-T, about 0.055" backlash on the Y-axis, very low (less than 5 mil) backlash on the X-axis. I installed a power drive on the X-axis (on the left side).

Praeger and Bill not really clear how much disassembly of the table(s) you did? Can all this work get accomplished without removing anything and just squeezing modified allen wrench and turning the loose screws? When the X-axis table was released, did you have to take off both hand (left and right) cranks and the bearings that hold the lead screw?

I will take a closer look maybe stick in a flexible camera to get a better view. Annoying... I was expecting better QA.

Ariel

Ariel, I keep telling you, you should buy German engineering. Taiwan is chasing the "value engineering" curve to compete with the motherland.

Das est gut.