Bearing part numbers and service tips for the DeWalt 788

[CharleyL]

Here is a list of the small VXB bearing part numbers for the DeWalt 788 Scroll Saw, and it's likely that the similarly designed Porter Cable and Delta scroll saws also use the same bearings. This is not my list. I managed to loose the good complete list that I made along with my invoice from the bearing store where I bought them, so this is a re-post of someone else's list.

 

 

 

Here are the VXB Bearing part numbers

 

These bearings can be sourced from VXB Bearings (800) 928-4430 , but most bearing stores also stock these or can get them for you. They will cost less through other sources than buying them from DeWalt or ereplacementparts.com as spare parts.

http://www.vxb.com/p...earings/PROD...

Kit8616 (HK0609 Needle Bearing 6x10x9)          qty needed 12
Kit7492 (HK0810 Needle Bearing 8x12x10)        qty needed   2
Kit7189 (HK1412 Needle Bearing 14x20x12)       qty needed  2

 

When I bought the full set of bearings for my DeWalt I asked the counter man at the bearing store if he had any higher quality bearings for any on my list and he said "Oh yea" and then filled my list from them. Many bearings are made by different manufacturers and some are better quality than others. All have identical part numbers, but sometimes with different suffix letters after the part numbers. These guys know who makes the better quality, tighter tolerance bearings and will give you better ones if you ask, but it may cost slightly more than the cheapest ones. Unfortunately, I don't have the invoice so I can't tell you what I ended up with, but my saw was much quieter than the new DeWalt saw of a friend's after I replaced them all. 

 

The larger sealed bearings that are located near the motor (the ones in the connecting rod and rocker arm) "must" be pressed out to be replaced. DeWalt sells these assemblies complete with the bearings already pressed in.

 

The www.ereplacementparts.com numbers for these are

 

Rocker Arm Asm                       286268-00     present USA price   $63.83 

Connecting Rod Asm                286280-00     present USA price   $28.82   

 

But if you have an arbor press like this one from Harbor Freight    http://www.harborfreight.com/1-ton-arbor-press-3552.htmlor a larger drill press, you can press out the old bearings and press in the new ones and save considerable money. When I replace bearings in my shop tools, my lawn mower, cars, etc. I use my bearing press frequently. So for me, this bearing press paid for itself very quickly. In the two assemblies above, I don't think there is $20 worth of bearings in them, so you can see how quickly this press can pay for itself if you have a frequent need. Bearings are very hard to keep straight while pressing them in and out without using one of these presses, and it's easy to crack aluminum castings if you should get a bearing crooked while pressing it in or out. I usually press the old bearing out, while at the same time pressing in the new one. You may also find that a bearing press will help sometimes with the smaller bearings too, especially if you don't have much or any experience changing bearings.

 

 When I need DeWalt replacement parts, I usually buy from www.ereplacementparts.com because they have always been good to me. 

 

Sorry, since I lost my bearing list, I don't have the bearing numbers for the larger bearings any more. You will need to get them from the bearings in your DeWalt saw or wait until I or someone else performs maintenance on our saws again and posts these numbers. They are etched into  the side of these bearings (very small - you will need magnification). The list above are the bearings that will likely wear out more frequently anyway.

 

Every bearing that rocks back and forth constantly without making a full revolution (all except for the bearing at the motor shaft end of the connecting rod) will have it's lubricant gradually driven out of the load areas by this rocking motion. Once the lubrication is gone from these load areas, the bearing balls or needles and the bearing races (inner and outer ring) begin to wear. Fortunately, the little HK bearings used in the 788 have a removable center race (sleeve), so this sleeve can be removed and a tiny bit of synthetic instrument grease added (I use a tooth pick as an applicator) to the inside of the bearings through the center hole (wipe the grease onto the needles in the sides of the bearing hole, and then the sleeve (which is the inside bearing race) can be replaced. When you do this, spin the sleeve a few revolutions to distribute and mix this new grease with the original grease before replacing and securing the bolt. I use Blue Locktite to secure bolts (absolutely do not use Red or Orange)  Also try to position the sleeve so it is not in the exact same orientation as it was before you removed it. Then replace the bolt or pin through the center of the bearing and secure it.

 

In bearings that rotate 360 deg, the lubricant is pushed ahead of the balls or needles inside it, and is constantly being redistributed around the entire inside of the bearing. They will last much longer without any attention than the ones receiving a repeating motion of less than one revolution. Unfortunately, by the design of a scroll saw, only the bearing in the motor end of the connecting rod assembly receives a continuous 360 deg motion. All of the rest of the bearings receive the partial back and forth motion, the motion that is so hard on bearings. All that we can do to prevent them from wearing out too quickly is to add some light synthetic grease  to their insides during scheduled maintenance.   
 

 

Only remove one side cover from your saw at a time. Removing both side covers at the same time will cause your saw to fall apart. There is no internal frame in the DeWalt or similarly designed Porter Cable and Delta Scroll Saws. The saw will fall apart if you remove both covers at the same time. Also, dis-assemble only one small assembly of the saw at a time to be certain that you can put it back together the same way before moving to the next assembly. With a cell phone or small camera, pictures can be taken before dis-assembly, to make putting it back together the same way much easier on your memory and the saw.

 

In addition to doing the bearings for general maintenance, check the condition of the bolt that connects the vertical rocker piece and connecting rod, back near the motor. This bolt receives a lot of force and can loosen or break. I replaced my bolt the last time that I had my saw apart. Some have reported that their bolt loosened, bent, or broke. So check it's condition carefully and replace it if necessary. It's a metric M5 cap screw that can be found in the better hardware stores, Lowes, and Home Depot, and it isn't expensive. Buy one the exact same length. These are available as stainless bolts too. Either black or stainless cap screw should work very well.

 

While your saw is apart, look around for other moving parts beside the bearings and put a little oil on them. The shaft through the center of the Rocker Arm has a sleeve that could stand a little oil. Again, use a high quality light weight oil for this. I use Tri Flow. There are other places for this oil, but I don't have them memorized.

 

Charley 

 

[Karl S]

Good Information Charley, Thanks for posting it for us.

[amazingkevin]

Here is a list of the small VXB bearing part numbers for the DeWalt 788 Scroll Saw, and it's likely that the similarly designed Porter Cable and Delta scroll saws also use the same bearings. This is not my list. I managed to loose the good complete list that I made along with my invoice from the bearing store where I bought them, so this is a re-post of someone else's list.

 

 

 

Here are the VXB Bearing part numbers

 

These bearings can be sourced from VXB Bearings (800) 928-4430 , but most bearing stores also stock these or can get them for you. They will cost less through other sources than buying them from DeWalt or ereplacementparts.com as spare parts.

http://www.vxb.com/p...earings/PROD...

 

Kit8616 (HK0609 Needle Bearing 6x10x9)          qty needed 12

Kit7492 (HK0810 Needle Bearing 8x12x10)        qty needed   2

Kit7189 (HK1412 Needle Bearing 14x20x12)       qty needed  2

 

When I bought the full set of bearings for my DeWalt I asked the counter man at the bearing store if he had any higher quality bearings for any on my list and he said "Oh yea" and then filled my list from them. Many bearings are made by different manufacturers and some are better quality than others. All have identical part numbers, but sometimes with different suffix letters after the part numbers. These guys know who makes the better quality, tighter tolerance bearings and will give you better ones if you ask, but it may cost slightly more than the cheapest ones. Unfortunately, I don't have the invoice so I can't tell you what I ended up with, but my saw was much quieter than the new DeWalt saw of a friend's after I replaced them all. 

 

The larger sealed bearings that are located near the motor (the ones in the connecting rod and rocker arm) "must" be pressed out to be replaced. DeWalt sells these assemblies complete with the bearings already pressed in.

 

The www.ereplacementparts.com numbers for these are

 

Rocker Arm Asm                       286268-00     present USA price   $63.83 

Connecting Rod Asm                286280-00     present USA price   $28.82   

 

But if you have an arbor press like this one from Harbor Freight    http://www.harborfreight.com/1-ton-arbor-press-3552.htmlor a larger drill press, you can press out the old bearings and press in the new ones and save considerable money. When I replace bearings in my shop tools, my lawn mower, cars, etc. I use my bearing press frequently. So for me, this bearing press paid for itself very quickly. In the two assemblies above, I don't think there is $20 worth of bearings in them, so you can see how quickly this press can pay for itself if you have a frequent need. Bearings are very hard to keep straight while pressing them in and out without using one of these presses, and it's easy to crack aluminum castings if you should get a bearing crooked while pressing it in or out. I usually press the old bearing out, while at the same time pressing in the new one. You may also find that a bearing press will help sometimes with the smaller bearings too, especially if you don't have much or any experience changing bearings.

 

 When I need DeWalt replacement parts, I usually buy from www.ereplacementparts.com because they have always been good to me. 

 

Sorry, since I lost my bearing list, I don't have the bearing numbers for the larger bearings any more. You will need to get them from the bearings in your DeWalt saw or wait until I or someone else performs maintenance on our saws again and posts these numbers. They are etched into  the side of these bearings (very small - you will need magnification). The list above are the bearings that will likely wear out more frequently anyway.

 

Every bearing that rocks back and forth constantly without making a full revolution (all except for the bearing at the motor shaft end of the connecting rod) will have it's lubricant gradually driven out of the load areas by this rocking motion. Once the lubrication is gone from these load areas, the bearing balls or needles and the bearing races (inner and outer ring) begin to wear. Fortunately, the little HK bearings used in the 788 have a removable center race (sleeve), so this sleeve can be removed and a tiny bit of synthetic instrument grease added (I use a tooth pick as an applicator) to the inside of the bearings through the center hole (wipe the grease onto the needles in the sides of the bearing hole, and then the sleeve (which is the inside bearing race) can be replaced. When you do this, spin the sleeve a few revolutions to distribute and mix this new grease with the original grease before replacing and securing the bolt. I use Blue Locktite to secure bolts (absolutely do not use Red or Orange)  Also try to position the sleeve so it is not in the exact same orientation as it was before you removed it. Then replace the bolt or pin through the center of the bearing and secure it.

 

In bearings that rotate 360 deg, the lubricant is pushed ahead of the balls or needles inside it, and is constantly being redistributed around the entire inside of the bearing. They will last much longer without any attention than the ones receiving a repeating motion of less than one revolution. Unfortunately, by the design of a scroll saw, only the bearing in the motor end of the connecting rod assembly receives a continuous 360 deg motion. All of the rest of the bearings receive the partial back and forth motion, the motion that is so hard on bearings. All that we can do to prevent them from wearing out too quickly is to add some light synthetic grease  to their insides during scheduled maintenance.   

 

 

Only remove one side cover from your saw at a time. Removing both side covers at the same time will cause your saw to fall apart. There is no internal frame in the DeWalt or similarly designed Porter Cable and Delta Scroll Saws. The saw will fall apart if you remove both covers at the same time. Also, dis-assemble only one small assembly of the saw at a time to be certain that you can put it back together the same way before moving to the next assembly. With a cell phone or small camera, pictures can be taken before dis-assembly, to make putting it back together the same way much easier on your memory and the saw.

 

In addition to doing the bearings for general maintenance, check the condition of the bolt that connects the vertical rocker piece and connecting rod, back near the motor. This bolt receives a lot of force and can loosen or break. I replaced my bolt the last time that I had my saw apart. Some have reported that their bolt loosened, bent, or broke. So check it's condition carefully and replace it if necessary. It's a metric M5 cap screw that can be found in the better hardware stores, Lowes, and Home Depot, and it isn't expensive. Buy one the exact same length. These are available as stainless bolts too. Either black or stainless cap screw should work very well.

 

While your saw is apart, look around for other moving parts beside the bearings and put a little oil on them. The shaft through the center of the Rocker Arm has a sleeve that could stand a little oil. Again, use a high quality light weight oil for this. I use Tri Flow. There are other places for this oil, but I don't have them memorized.

 

Charley 

A light went on in my head yesterday.Why can't a drill press be used as a bearing press?Using sockets the right size either metric or sae?

[CharleyL]

Yes, you can use socket wrench sockets of the right size to press bearings, but be careful to only press against the outer race of the bearing with something just slightly smaller than the bearing diameter, or you might discover that you now have installed the socket wrench socket into where the bearing should be, or if too small you have damaged the side cover of the bearing. There are specially designed sets of bearing pushers like this one https://www.amazon.com/Sunex-3920-Seal-Bearing-Driver/dp/B001A4986W/ref=sr_1_4?ie=UTF8&qid=1479208189&sr=8-4&keywords=wheel+bearing+tool+set. I'm not recommending this set, but it shows what they look like. I don't own a set myself. I usually just look around to find something the right size, or modify something to make it the right size, and then use it.

 

I usually just use the new bearing to push out the old one, while at the same time pushing in the new one. This is usually the best, and safest way. The only thing critical is that you push it straight in, so it doesn't bind or crack the part you are installing the bearing into. When I've used my floor standing drill press, I use an old engine valve with the valve stem chucked into the drill press This gives me a very flat bottom surface to push against the bearing to push it straight in.

 

You also need a way to support the piece receiving the bearing closely around the bearing from below, but just slightly larger than the bearing diameter, so you don't install the old bearing into it. It needs a cavity to catch the old bearing or a hole to let it drop through as it's pushed out though. Finding the right wrench socket to use for this is usually much easier than finding the right one to use above to push the old bearing out or the new bearing in. In most cases the automotive valve's flat surface can be used to push directly against the new bearing, and you don't need any kind of adapter. However, you won't be able to push in a bearing this way if the bearing design includes a center race that is taller than the outer race when the bearing is laying flat on it's side, or the bearing is located very close to a protrusion in the part's casting. Fortunately, the bearings designed like this are quite rare. There aren't any bearings like this in the DeWalt 788, or in the similar Porter Cable and Delta scroll saws that I know of.

 

If you have problems pressing in the new bearing, put it in the freezer for an hour, and then quickly install it while it's still very cold. The lower temperature will make the bearing temporarily slightly smaller in diameter, so it will press in much easier. The alternative is to slightly heat the piece that the bearing is going into, to make the bearing hole slightly larger in diameter, but freezing the bearing is the safer alternative for both the bearing and you. Tight fit bearings are usually the result of significant overheating during the bearing's life. I doubt that you will ever have this problem in a scroll saw. I haven't run into this problem in any woodworking tool that I've ever replaced bearings in, but have had to perform all kinds of magic and tricks to replace some bearings in automotive vehicles.

 

Charley

[meflick]

Thanks for sharing your detailed information Charley.  I will have to see if my hubby is willing to look at and service the Dewalt I have.  It started making some noises a while back but I clearly don't have the knowledge or expertise myself.  He does a lot of mechanical repair work around the house (though that is not what pays the bills) so he might be willing to look into this for me if I can give him such good info.     

[CharleyL]

Melanie,

 

If the noises just started, all they likely need is grease. It's quite simple to identify each of these small bearings, remove the one bolt through it and then the sleeve insert, apply a small bit of synthetic grease to the sides of the bearing hole with a tooth pick (I like the ones with one end flattened - makes a great grease shovel), and then replace the sleeve and rotate it a couple of times before replacing the bolt. Use a small bit of Blue Locktite on the bolt threads near the end of the bolt and screw it back in. Tighten it with about the same force needed to remove it. Then go on to the next tiny bearing and repeat the steps. In less than 1/2 hour, all of the little bearings will have been greased.

 

Before putting the cover back on, rotate the motor a few revolutions using a screwdriver to turn the back end of the shaft while watching the pieces move inside the saw. It will be easy to see where to add a tiny bit of Tri Flow or similar light machine oil (places where movement occurs between parts but don't have bearings). Also watch the larger pieces with the larger bearings back near the motor to see if you can locate any problems with those bearings, or that critical bolt through the connecting rod and rocker arm. If you do, you need to fix or replace these parts and/or bearings. Any unusual side to side or up and down movement between the inner and outer race of these bearings indicates a bad bearing that must be replaced. They will usually begin to make noise long before you see any unusual movement in them, but not always. 

 

This is a good time to check the motor brushes too. Carefully remove the little black caps on the front and back side of the motor. There is a spring underneath, so be careful to hold onto the cap as you unscrew it. With the cap off, pull the spring out, and on the other end of the spring is a square black piece. This is the actual motor brush. Note that the end of this brush is curved. You want to put it back in with this curve in the same orientation, because it rubs on a curved part inside the motor. The new brushes come with the springs attached. New brushes don't have the curved end, but will wear to this shape as they are used. A new brush can be put in in any orientation, so long as the brush goes in first, followed by the spring and cap. You have to buy the little caps separately if you loose one. I keep a set of brushes and brush caps in my scroll saw tool box. I also keep replacement fuses and at least one cap for the fuse holder. If I'm at a show or class session I don't want to be without any of these.

 

As the brushes wear, the black pressed carbon piece gets gradually shorter. You don't want to ever let this get so short that the spring touches without a brush piece on the end of it or the motor will be history. I replace my brushes when they get about 1/4 - 3/8" long, which is several years of safety factor under normal use, but checking them frequently can save the need for a motor replacement. New brushes are cheap. A new motor isn't. Todays USA price for the motor from www.ereplacementparts.com is $282.68 plus shipping. You can frequently find a really good condition used 788 saw for that or less.

 

 

How fast do you run your saw ? Running very fast will do nothing except give you short blade life and a worn out saw. I run my saw as fast as I can and still have full control of the cut and without overheating the blade and burning the sides of the cut. This almost always means a slow, like a 2-3 setting on the speed dial. If you adjust it for this speed and the blade goes dull it will begin burning the sides of the cut and the blade will get hot, removing the temper of the blade and making it get dull even quicker, so as the blade dulls, you need to slow the saw down even further. Keep your blade from turning blue and you will get the longest life possible from the blade and the saw. I replace my blades when they get dull. I don't break them very often, and my most frequently used blades are #1 and 1/0 reverse tooth Flying Dutchman blades. I do a lot of small compound 3D cutting in mostly hard woods. In hard maple, one of these blades will become too dull for me to use in less than about 30" of cut. You may get more. You may get less. It will depend a lot on what you are cutting and how fast you are trying to cut it. At about $0.20 per blade I don't worry about the cost and strive for the best quality of cut that I can get, and I expect to have to change the blade often to get this quality. When I take a blade out of the saw, I never save it, even if it was used only a very short time. It's too easy to loose track of this imperfect blade's size, type, and sharpness. I would rather just install a new blade of known size and sharpness.

 

Charley

[Bill WIlson]

Great information Charley!  Thanks for posting this. 

 

For those of you with Excaliburs, have you ever greased the bearings?  I presume they are similar to the DeWalt, but haven't investigated it.  I had my DeWalt for over 10 years and never had a problem, but I don't put the hours on my saw that many of you folks do.  I figure it will be at least that long before my EX would develop any issues, but one never knows. 

[meflick]

Thanks for the additional Information Charley.  Since hubby is the mechanically inclined one, I will get him to help me check it out based on your information provided here when he has some time.