Table Saw Jet JTAS-10DX
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General
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Blade Raise/Lower Mechanism Damage/Failure in July of 2023
In early 2023 (after COVID) this table saw was receiving heavy use without users paying attention to dust collection needs. An accumulation of compacted sawdust filled the inside of the saw base. The handwheel that raises/lowers the blade became hard to turn. Continued use in this condition caused wear in the worm gearing and gear tooth damage. A new part (#114) Arbor Bracket JTAS10DX-114 was ordered and replaced.
By July of 2023, that same new part (#114) Arbor Bracket JTAS10DX-114 that was installed was again fatally worn and damaged the same way. The root cause for this damage had not (yet?) been found.
On July 23, 2023 a LVL1 email chain thread was started between GaryF, LarryR, JeffM, JimD, BillS, and TiffH to discuss and identify the root cause of the repeated Table Saw failure. The following [TL:DR] is from that email discussion.
Here is the {link} to the table saw's full 28-page manual as a PDF file.
Here is the {link} to three color-highlighted pages (just pages 23, 24, and 25) from the above 28-page manual. The color highlights identify different portions of the saw's parts list and assembly drawing as a troubleshooting repair reference.
Anthony from Jet Tech Service (ph: 800.274.6846) was contacted for a phone discussion. He is one-of-six that address woodworking equipment calls. He did not see any prior LVL1 contact info in his call records, so others of us may have been speaking with others in their group. Anthony provided good details and is available if we need a call back.
- Point 1 = We are on the right track needing to replace both of the blade raise/lower “gear” parts due to mutual tooth profile wear.
Index No. Part No. Description Added notes 114 JTAS10DX-114 Arbor Bracket Has ‘worm wheel’ teeth 146-1 JTAS10DX-146 Worm (Right Thread) Correct 1-of-2 different worms
- Point 2 = This table saw has two different WORM part numbers. BillS identified the correct one in his email above and shown below for the raise/lower function and not for the tilt function.
Index No. Part No. Description Added notes 146 JTAS10-146 Worm (Left Thread) Tilt Blade 146-1 JTAS10DX-146 Worm (Right Thread) Raise/Lower Blade <- BillS is correct
- Point 3 = We understand correctly there is no adjustment for the worm gear set depth of tooth engagement. Holes in the three bolted-together yoke/trunion parts #152, #141, and #139 (shown in orange) establish the worm set center spacing via shaft #121 (yellow) and shaft #144 (green).
Anthony also said we should examine our front/rear bushing parts #140 and #140-1 (both green). It is possible to have excessive wear in these bushings, and that can affect the position of Shaft #144 and Worm #146-1 (both green) relative to Arbor Bracket #114 (yellow). We can order these additional bushing parts, if necessary.
- Point 4 = It is hypothesized that our noted BINDING/GRINDING in the blade raising/lowering mechanism could come from issues at any of the following five possible interfaces.
4a = Shaft #144 (green) should rotate freely without wobble in Front Bushing #140-1 (green) located in the hole in the Front Trunion #152 (orange).
4b = Shaft #144 (green) should rotate freely without wobble in Rear Bushing #140 (green) located in the hole in the Rear Trunion #139 (orange).
4c = Collar #143 (green) and Fiber Washer #138 (green) function as an axial thrust bearing for Shaft #144. These parts, with a second Fiber Washer #138 (green) and Hex Nut #137 (green) capture Rear Bushing #140 (green) in its hole in Rear Trunion #138 (orange). These parts should be adjusted to enable Shaft #144 (green) to rotate freely without axial play and accept axial thrust loads from the Worm #146-1 (green).
4d = Shaft #121 (yellow) fits into two holes in Yoke #141 (orange). Motor Bracket #122 (yellow) fits onto Shaft #121 (yellow) between these two holes and is located via Spring Pin #117 (yellow). Pin #123 (yellow) with Screws #120 (yellow) and Flat Washers #119 (yellow) fit into Motor Bracket #122 (yellow) to attach Motor Mounting Bracket #126 (yellow) with the Motor #131 (yellow) and Motor Pulley #127 (yellow). These assembled parts should rock freely on Shaft #121 (yellow).
4e = Arbor Bracket #114 (yellow) mounts onto the extended end of Shaft #121 (yellow) via three Wave Washers #107 (yellow), Key #112 (yellow), Socket Head Cap Screw #111 (yellow) and Lock Washer #113 (yellow). Shaft #121 (yellow) with all these assembled parts should rock freely within the two holes in Yoke #141 (orange).
- Point 5 = If you think about the three features in Arbor Bracket #114 (green) and related parts you will gain the following insights.
5a = Because of gravity, the Motor #131 (yellow) wants to fall down.
5b = The motor is primarily supported by Motor Bracket #122 (yellow)
5c = The drop of the motor is limited by tension in the Poly V-Belt #125 (yellow) with Arbor Pulley #110 (yellow) and Motor Pulley #127 (yellow).
5d = Since the Arbor Pulley #110 (yellow) is attached via Arbor with Flange #104 (yellow) the downward force of the motor weight causes Arbor Bracket #114 supported on Shaft #121 (yellow) to want to rotate counter-clockwise (viewed from right to left) around Shaft #121 (yellow).
5e = Without opposition, this action causes the blade raise/lower mechanism default position to be down/lowered.
5f = The Worm #146-1 (green) provides the opposition to raise/lower and maintain the blade height at a chosen height.
5g = The gravity force on Worm #146-1 (green) is transferred to Shaft #144 (green), wanting to push the shaft towards the back of the saw.
5h = The axial position of the Shaft #144 (green) is maintained by Shaft Collar #143 (green) and related parts to Hex Nut #137 (green) at Rear Bushing #140 (green) mounted in the hole in Rear Trunion #139 (orange).
- Point 6 = Shaft #144 (green) can be extracted without disassembly of the three bolted-together yoke/trunion parts #152, #141, and #139 (shown in orange).
6a = Remove Hex Nut #137 (green) and 1of2 Fiber Washer #138 (green) from the end of Shaft #144 (green).
6b = Loosen Collar #143 (green) and 2of2 Fiber Washer #138 (green) at Rear Bushing #140 (green) on Shaft #144 (green).
6c = Remove Spring Pin #145 (green) that holds Worm #146-1 (green) in place.
6d = Loosen Lock Knob #155 (green) to retract the two Lock Pins #147 (green) into the interior of Shaft #144 (green) and below the shaft’s outer surface.
6e = Pull the Handwheel #160 (green) with assembled parts including #162, #163, #164, #165 (all green) , and attached Shaft #144 (green) out from Front Bushing #140-1 (green) that is in the hole in Front Trunion #152 (orange). Fiber Washer 2of2, Collar #143, Worm 146-1 (all green) will come off Shaft #144 (green) as it is pulled through Front Bushing #140-1 (green).
