amazingkevin Posted July 22, 2016 Report Share Posted July 22, 2016 I wanted to scroll today but the racket coming from a normally quite saw has been driving me bananas.Finally i had to get to the bottom of at least one of them what was wrong.Ends up the one im using now had a bolt and nut come off or loose.You could hardly scroll an inch and the blade would break.i'll bet that's what's wrong with all of them .Same problem with each.What i think is the people that bought their DW788 had no idea on blade tension and left it sloppy and ran the machine wide open for there project.The vibration from the blade being to loose would cause something to come apart i would think.any way i took the machine apart and lo and behold here's the nut and washer and the bolt 3/4' out of the wrist pin of the connecting rod.I just ran across my loc tite but as usual when you need it you can't find it .So i put the parts back wher they go and buttoned it up ,Put a blade in and turned it wide open .No noise no vibration.so i'm good to go a little while longer.Next time i find the loc tite i'm going to hang it on a string,lol Quote Link to comment Share on other sites More sharing options...
ike Posted July 22, 2016 Report Share Posted July 22, 2016 good going. IKE Quote Link to comment Share on other sites More sharing options...
Scrolling Steve Posted July 22, 2016 Report Share Posted July 22, 2016 Nice save Kevin ! Quote Link to comment Share on other sites More sharing options...
jerry1939 Posted July 23, 2016 Report Share Posted July 23, 2016 Kevin, That's the same bolt that spit in the middle on my Delta a couple of weeks ago. I replaced it with a stainless steel bolt from a local hardware store. Stainless is usually a harder metal. Stupid design flaw to put the entire load of the saw on that one undersized bolt. jerry Quote Link to comment Share on other sites More sharing options...
CharleyL Posted July 23, 2016 Report Share Posted July 23, 2016 Yup, I've been there too. I now keep a spare, and blue Lock Tite handy. (Everything that I take apart that I don't want to come apart on it's own again gets blue Lock Tite). Its definitely the weakest point in a 788. Keep it tight and you should go longer between repairs and replacement. The next weak link for me has been that bearing on the motor shaft. Everything else seems to last a long time if you add some synthetic grease to the bearing needles (pull the sleeves out to add it) every now and then. Kevin, I would not be at all surprised if this was a problem in all of your saws. It may not be the only problem, but it is likely the main one. I'm not sure I like the stainless idea, but definitely a new bolt and nut, with blue Lock Tite. Charley amazingkevin 1 Quote Link to comment Share on other sites More sharing options...
meflick Posted July 23, 2016 Report Share Posted July 23, 2016 Thanks for sharing Kevin. God to know. I will have to keep this in mind if my Dewalt 788 starts sounding bad or acting up. Quote Link to comment Share on other sites More sharing options...
WayneMahler Posted July 23, 2016 Report Share Posted July 23, 2016 Good job Kevin. Quote Link to comment Share on other sites More sharing options...
Lucky2 Posted July 23, 2016 Report Share Posted July 23, 2016 Kevin, thankfully it was a quick and cheap fix. Len Quote Link to comment Share on other sites More sharing options...
amazingkevin Posted July 23, 2016 Author Report Share Posted July 23, 2016 good going. IKE I've taken DW788's apart more times than i want to ,It's easy but time consuming.It would be nice if they were more of a 2 or 3 piece unit instead of everything holds everything else together.Thanks IKE, back in business Quote Link to comment Share on other sites More sharing options...
amazingkevin Posted July 23, 2016 Author Report Share Posted July 23, 2016 Nice save Kevin ! While i had it apart i wanted to regrease things but since the move i've not found a lot of things so far. Quote Link to comment Share on other sites More sharing options...
amazingkevin Posted July 23, 2016 Author Report Share Posted July 23, 2016 Kevin, That's the same bolt that spit in the middle on my Delta a couple of weeks ago. I replaced it with a stainless steel bolt from a local hardware store. Stainless is usually a harder metal. Stupid design flaw to put the entire load of the saw on that one undersized bolt. jerry I know what you mean Jerry .I understand the ex saw is basically a dw788 only shaped different ,same interior parts exactly.I don't want to spend double the money for a new EX saw that is a dw788 in disguise. Quote Link to comment Share on other sites More sharing options...
New Guy Posted July 23, 2016 Report Share Posted July 23, 2016 Thanks for showing us the problem. You saved somebody trouble in the future. Quote Link to comment Share on other sites More sharing options...
amazingkevin Posted July 23, 2016 Author Report Share Posted July 23, 2016 Yup, I've been there too. I now keep a spare, and blue Lock Tite handy. (Everything that I take apart that I don't want to come apart on it's own again gets blue Lock Tite). Its definitely the weakest point in a 788. Keep it tight and you should go longer between repairs and replacement. The next weak link for me has been that bearing on the motor shaft. Everything else seems to last a long time if you add some synthetic grease to the bearing needles (pull the sleeves out to add it) every now and then. Kevin, I would not be at all surprised if this was a problem in all of your saws. It may not be the only problem, but it is likely the main one. I'm not sure I like the stainless idea, but definitely a new bolt and nut, with blue Lock Tite. Charley Ah were on the same page ,i like that,?i'm not sure if on my first DW788 if i regreased the motor bearing,Im guessing your referring to the connecting rod on the motor? All the bearings i could get to on the first saw got valvoline synthetic grease repack It made a new saw out of a wore out one for two years . gave it to my friend and he's still going strong with it.Thanks Charley for the heads up! Quote Link to comment Share on other sites More sharing options...
amazingkevin Posted July 23, 2016 Author Report Share Posted July 23, 2016 Thanks for sharing Kevin. God to know. I will have to keep this in mind if my Dewalt 788 starts sounding bad or acting up. If you start breaking blades very often thats a sign Quote Link to comment Share on other sites More sharing options...
amazingkevin Posted July 23, 2016 Author Report Share Posted July 23, 2016 Good job Kevin. Thanks Wayne ,i think some one was in this one as a spring washer was missing that i always make sure is on prior to assembly Quote Link to comment Share on other sites More sharing options...
amazingkevin Posted July 23, 2016 Author Report Share Posted July 23, 2016 Kevin, thankfully it was a quick and cheap fix. Len So far all the DW788 repairs were dirt cheap and from the big box store for screws ,nuts or bolts. Quote Link to comment Share on other sites More sharing options...
amazingkevin Posted July 23, 2016 Author Report Share Posted July 23, 2016 Thanks for showing us the problem. You saved somebody trouble in the future. Thanks Al ,Everybody here knows something about DW788's wheather it's finding schematics .parts,modifications ,we help each other keeprunning smooth Quote Link to comment Share on other sites More sharing options...
CharleyL Posted July 23, 2016 Report Share Posted July 23, 2016 Be careful, that bolt is a pivot point, so don't over tighten it. You have to allow that point to pivot. The stop nut nylon insert is supposed to hold the nut from backing off, but it doesn't seem to always work. I used the blue Lock Tite on the threads of a new nut and new bolt when I had the problem. I used a new nut to avoid any chance of the nylon insert not holding well because threads had already been formed in the nylon insert of the original nut. The blue Lock Tite on the threads of this new nut was added insurance to keep it from backing off. Sorry, I did this several years ago and had forgotten the details. Kevin, You can't grease the bearing on the eccentric cam of the motor. It's a sealed bearing. The ones that I've added grease to are the small ones with the sleeve insert. Remove the sleeve and add a tiny amount of synthetic grease inside the hole of the bearing to lubricate the needles. I used a tiny wooden round stick (I think they are called "applicator sticks" from the drug store). Only a thin coating of grease on the last 1/8" of the end of the stick is needed. Don't gob it on. Then replace the sleeve and rotate the sleeve several times to distribute the grease before putting the saw back together. The grease that doesn't go inside the bearing is waste. It won't do anything, except fly off and make a mess of the inside of the saw when the saw is running again, so wipe off as much of this excess as you can. Charley Quote Link to comment Share on other sites More sharing options...
amazingkevin Posted July 23, 2016 Author Report Share Posted July 23, 2016 Be careful, that bolt is a pivot point, so don't over tighten it. You have to allow that point to pivot. The stop nut nylon insert is supposed to hold the nut from backing off, but it doesn't seem to always work. I used the blue Lock Tite on the threads of a new nut and new bolt when I had the problem. I used a new nut to avoid any chance of the nylon insert not holding well because threads had already been formed in the nylon insert of the original nut. The blue Lock Tite on the threads of this new nut was added insurance to keep it from backing off. Sorry, I did this several years ago and had forgotten the details. Kevin, You can't grease the bearing on the eccentric cam of the motor. It's a sealed bearing. The ones that I've added grease to are the small ones with the sleeve insert. Remove the sleeve and add a tiny amount of synthetic grease inside the hole of the bearing to lubricate the needles. I used a tiny wooden round stick (I think they are called "applicator sticks" from the drug store). Only a thin coating of grease on the last 1/8" of the end of the stick is needed. Don't gob it on. Then replace the sleeve and rotate the sleeve several times to distribute the grease before putting the saw back together. The grease that doesn't go inside the bearing is waste. It won't do anything, except fly off and make a mess of the inside of the saw when the saw is running again, so wipe off as much of this excess as you can. Charley Thanks Charley, when i re grease bearings ,scroll saw or car i hand pack them in the palm of my hand till all the old grease is out.I love shop talk ! Quote Link to comment Share on other sites More sharing options...
Rolf Posted July 23, 2016 Report Share Posted July 23, 2016 (edited) I was going to suggest a nylock nut, but it was already suggested. Another caution to use the correct bolt when replacing it. You certainly don't want a sloppy fit in the bearing. If I remember correctly that part (connecting rod) has a needle bearing in it that rides on the bolt. so the bolt has to be hardened Not stainless. too soft. Spent lots of time with a hand full of wheel bearing grease packing bearings. I now wear gloves when I work on my 46 year old car. Getting to be a bit prissy in my old age. I refuse to work on my new one, that is what warranties are for. Edited July 25, 2016 by Rolf Quote Link to comment Share on other sites More sharing options...
Fish Posted July 23, 2016 Report Share Posted July 23, 2016 That's the part I just replaced. It is much smoother and quiet. Good to hear yours is working good, Quote Link to comment Share on other sites More sharing options...
jerry1939 Posted July 23, 2016 Report Share Posted July 23, 2016 Almost all the replies pertain to the nut coming off. As stated earlier, on mine the bolt sheared off just inside the nut. Re: replacing with stainless steel. Years ago I had a concrete saw that also took metal cutting blades. Stainless steel was harder and wore out the saw blades much faster. Have done a lot of mechanical work in my life, and if a bolt sheared that shouldn't, I have never found it to be a problem replacing it with something harder, but to each their own. jerry Quote Link to comment Share on other sites More sharing options...
heppnerguy Posted July 23, 2016 Report Share Posted July 23, 2016 Makes me want to go back into my old saw once again and refresh my mind as to what exactly is wrong with it. Thanks for your post Kiven Dick heppnerguy Quote Link to comment Share on other sites More sharing options...
amazingkevin Posted July 24, 2016 Author Report Share Posted July 24, 2016 Makes me want to go back into my old saw once again and refresh my mind as to what exactly is wrong with it. Thanks for your post Kiven Dick heppnerguy dick if it's a DW788 Take the blade out ,hold the top arm down and try to move the blade holding mechanisms up sand down.I you feel sloppy or at least a 1/2" play it's 99% the bolts nut fell off the connecting rods wrist pin,easy fix.Also while your holding the top arm down do the same test with the lower arms blade holding mechanisms Quote Link to comment Share on other sites More sharing options...
amazingkevin Posted July 24, 2016 Author Report Share Posted July 24, 2016 Almost all the replies pertain to the nut coming off. As stated earlier, on mine the bolt sheared off just inside the nut. Re: replacing with stainless steel. Years ago I had a concrete saw that also took metal cutting blades. Stainless steel was harder and wore out the saw blades much faster. Have done a lot of mechanical work in my life, and if a bolt sheared that shouldn't, I have never found it to be a problem replacing it with something harder, but to each their own. jerry your a good man Jerry ,good info! Quote Link to comment Share on other sites More sharing options...
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