Powermatic (AEM) model 250 Widebelt sander

crzypete · Post by **crzypete** » Tue Apr 12, 2011 10:17 pm

Hello Junkies, it seems it is time again for another studio upgrade. My AEM 12" narrowbelt has served me very well for the past number of years. ( http://machinejunkie.com/forum/viewtopic.php?t=328 ) But my needs have begun to consistently out capacity it and with several big projects coming up I set out to find a bigger machine.

I had my heart set on a 24" as a 36" is too big for me. I located one at RT machine in PA. They were asking too much and it needed some roller work. After researching the roller repair, I made them a low-ball offer. They actually accepted and yesterday I made the 11 hour round trip trek to pick it up.

here is RT Machine

Did you see this truck going down the road yesterday? I made sure to tarp it so it would not rain.

This is what is hiding underneath.

Just another day at the office for my crown lift.

The skies opened up and it poured about half an hour after I was unloaded- definitely a good omen. I went over the machine this morning and am happy with it so far. I do have to complain about the previous shop that owned it. A couple of simple repairs- less than ten minutes would have saved the machine both physical and visual damage- When something is broken just fix it!

Pete

crzypete · Post by **crzypete** » Wed Apr 13, 2011 9:18 pm

I titled this thread Powermatic (AEM) sander because the sander although badged and painted powermatic is actually an AEM in Powermatic clothing.

I bought it knowing that the main drive drum was going to need re rubbering. I priced it out ahead of time by calling Timersavers- who own AEM. The tech there said it was going to be an outrageous sum, but that I should find a place to deal with it locally. I followed his advice and received a favorable quote from finzer roller.

Here are some pics from going after the roller.

Step one was removing the covers

next up was removing the dust shroud

After the covers were gone, the disk brake needed to be pulled. The brake caliper was removed first and then the disk was pulled. Fortunately it was not rusted on too badly as I was not sure how to hook a puller to it.

Here it is with the brake disk removed. I turned the caliper around and bolted in place backwards for storage. The pulley is of a tapered hub design. The two set screws are removed and you can then drive one of them back into the third hole in order to split the bushing from the pulley.

It quickly pops apart and can be easily pulled.

The whole assembly that holds the two rollers and the platen have to come out. I put two 2 x 4's on the feed conveyer and raised the conveyer so the 2x4's contacted the drums, this allowed me to lower it in a controlled fashion once I took out the four socket head cap screws that held it in place. I used the bed adjust to get the height just perfect and begin to pull it out.

All was going well until I snagged something. It turned out to be the bottom of the air piston which tensions the belt. Here I use two wedges to raise the upper roller to get the needed clearance.

Finally out and on the workbench. Here is the damaged roller. the next step is taking apart this whole assembly. This turned out to be more interesting than expected.....

[/img]

crzypete · Post by **crzypete** » Thu Apr 14, 2011 9:58 pm

What came next was a sprawling mess. The bearings that the machine uses have clamp collars to attach themselves tot he shafts. I thought this would make pulling them pretty easy, I was mistaken. Even with the clamp collars released they were tight and I had problems as there was no good way to get a bearing puller on the assembly due to the castings that held the two rollers and platen in place.

Finally I found that I could remove the snap ring from the outer race of the bearing on the steel idler and then push that idler through one end.

Once that was accomplished, I was able to use a posi-lock puller to grab the bearing and remove it from the shaft.

next up is pulling the snap ring off of the rubberized drive drum.

That allows the casting to slide off

Here I use a larger bearing splitter and puller to get the bearing off the pulley side of the drive drum.

In pulling the machine apart, I found the motor to be hard to spin, so I pulled it for a bearing job. Upon opening it to de-wire it, I found that someone had been in there. The wires were labeled and I am suspicious.

Upon loosening the bell housings, the motor becomes easier to spin. Not a good sign, someone did not do a good job of putting this thing bak together.

The stator is pretty stuck in the front motor cap, so I use my shop press to squeeze it out.

and back to the big bearing splitter and puller. In my favor is that the bearings have not been replaced and the smaller one is stiff. Hopefully new bearings and a good cleaning will have this motor back up to snuff.

This was all yesterday, Today I was pretty busy, but did get a chance to position the machine in its final home. It feels like a good fit.

crzypete · Post by **crzypete** » Mon Apr 25, 2011 10:41 pm

Continuing on...

I decided to pull the bearings from the top drum as well. I figure I may as well swap the even though they felt fine as I want to do this work once and be up and running for a long time. The bearings are in pillow blocks that are of a unique design to the brand sealmaster. AEM used sealmaster bearings extensively in their machines as I can now attest to having worked on two different AEM sanders. The distinguishing characteristic of the sealmaster bearings is they have a clamping collar that locks on the shaft that they attach to.

I ended buying a bunch of sealmaster bearings from eBay and today some arrived. Including the ones that I speculated would fit the pillow blocks for the upper drum. They were not quite the same but pretty close, and I determined they would work so I set about pulling the second pillow block and replacing the bearings.

I mentioned that the pillow blocks were unique, most pillow blocks I have seen have wings which bolt down, these are particularly narrow and have tapped holes in their base. They also have a ring on the locking collar on the bearing.

I used my bearing splitter/puller to remove the pillow block from the shaft and stuck the pillow block into my large bench vise. I then found an appropriately size piece of stock to fit the bearing.

The bearings fit into pillow blocks in a spherical system, this allows the bearing to adjust if the blocks are not quite aligned. It makes for an interesting removal. They get tilted to be removed.

Here it is at about 90º to the block

The back side has two notches which allow the bearing to come right out.

Here is the new bearing getting ready to go back in. The bearings I bought as replacements don;t have the locking collar- they simply use setscrews. This is not quite as desirable to me, but since it is the upper drum, I am accepting.

going back in

and seated.

Back on the shaft and mounted in the sander. Looking at it now, I wonder if I have it backwards!

Just a note on Sealmaster bearing nomenclature for the next person who is planning on ordering these.

-They are sized by the shaft that they fit in 16ths of an inch, so the er-16 bearings I bought are 1" ID. The OD's seem to only come in one size per ID.

-The fancy locking collar is indicated by a "t" in the bearing number, so an er-16 has the set screws and an er-16t has their fancy locking collar.

-The er's I have been mentioning are the bearings that fit the two lower shaft, The ones that fit the pillow blocks have other lead letters, but the 16 remains the same.

DenaliPilot · Post by **DenaliPilot** » Thu Apr 28, 2011 4:24 am

What do you think caused that damage to the rubber roller?

crzypete · Post by **crzypete** » Thu Apr 28, 2011 7:32 am

Hey DP,

If I had to venture a guess I would think it was a stray knot from a board that broke loose. The rest of the roller seemed to be ready for a refresh as well, so perhaps not the end of the world, although, I did have good luck in simply turning my the roller on my old machine to expose fresh rubber.

Hopefully the roller is well on its way to being fixed, I need to check in with Finzer http://www.finzerroller.com/ to see the progress. The last of my bearings should be showing up today.

Pete

crzypete · Post by **crzypete** » Sat May 07, 2011 9:24 pm

The word from finzer is slow and possibly behind schedule

Truthfully I am busy enough in the shop that I do not need the work of getting the sander back together, but I am certainly eager to do it and want it to be on my schedule rather than theirs.

I talked to friend who mentioned another company as a potential source to have this kind of work done http://www.imr-inc.com/ He had just sent a roller to them, but had not yet received it in return.

Pete

crzypete · Post by **crzypete** » Sun Sep 25, 2011 10:51 pm

Ok, well now I am the one who is slow and way behind schedule.

The roller came a while ago, a long while ago. I installed it not long after that while ago.

Here is a pic of the roller when it came back

It was not quite the same groove pattern, but looked great

Installation with new bearings was easy and I thought I was well on my way.... problems are ahead!

Next up was the mundane task of replacing the felt and graphite on the platen. Timesavers didn;t have the original specs of what they used and I ended up using a 1/4" thick felt from mcmaster carr- F3 grade the hardest reasonably priced felt they stock. I have since figured out that I would be better with 1/8" thick felt, as I cannot seem to fully back the platen out of the way. I bought graphite covered canvas from klingspor, here is the installation:

With felt applied

Attaching the graphite to the first side:

Wrapped around and attached the the far side. I found it was helpful to have extra wide graphite that could be stretched like you would upholster a chair.

and trimmed to size

crzypete · Post by **crzypete** » Sun Sep 25, 2011 11:04 pm

Continuing along, now months later, it is towards the end of august. I actually wire the machine add a second idler motor to my phase converter- an additional 7.5 hp to my 10 hp converter.

Finally I am ready to run my sander for the first time.

and then

as the conveyer feeds around I find a beautiful smile at the seam. Guess I should have found where that was when I was buying it.

I did some research and ordered a new conveyer directly from timesavers- it was a remarkably cheap $202. It Arrived this past week, so this next section is pretty recent.

Again I call on my favorite friend the crown lift Definitely the best way to remove the table from the machine.

Once removed I hook up a big wrench to the tensioning bolts and drop the tension

I clean up the innards and get the new belt on with little effort.

It turns out that the ways are made of brass and worn and wallowed. I decide to straighten them in my shop press prior to milling them.

This is best done with a number of steps of increasing pressure so you do not overshoot the target. It actually takes a good amount of pressure to get them straight, you can really see the flex in this shot.

The it is off to the mill to really get it perfect

[/img]

crzypete · Post by **crzypete** » Sun Sep 25, 2011 11:19 pm

In performance testing I find that the variable speed conveyer drive is tripping its magnetic switch. I am unable to diagnose an electrical problem, so I this weekend I decide to take it apart in search of a bad bearing.

Here I pull a pulley with my biggest posi lock puller. It is actually quite overkill, but Damn nice to use.

If I doing a good job of documentation I would have taken a bunch of pictures on how I pulled the blind bearing with a makeshift slide hammer, but alas, I dropped the ball so all you get is a picture of the oily innards.

Within the unit I found 3 bad bearings, they still spun, but had seen better days. I am lucky to have had all three in stock and the box is almost back together- my stock on gear oil was not as fortunate as my bearing supplies. Hopefully this will solve the issues. The Reeves pulleys were pretty dry of grease on their shafts and I feel good about the work I have down here even if this is not the final solution to the tripping starter.

I feel like the rebuild has been mechanically very involved with almost zero attention to the aesthetics, My baby 12" machine is probably ashamed that this ugly beast is what is replacing it, but so far the finish results have been excellent, and the extra width has become more important to my work.

Pete

nektai · Post by **nektai** » Mon Sep 26, 2011 7:36 am

Nice work Crzy.

My AEM 12" has undersized table ways and a replacement motor and drive for the table. Two areas that they could have improved. You WILL benefit from the work that you have done