Alignment / Adjustment of dual lift P/T tables:
The Jet family of P/Ts with dual-lift, or 'raise-together' tables has a UK manual lacking adjustment instructions. This is a problem, as the tables will require periodic checking and adjustment to allow for wear. The USA manual which can be downloaded from Jet's N. Amreican website, is a little better but still lacks some important details.
Dual Lift Table Mounting System:
Looked at from the operating position, each table is supported by a hinge at the back, and rests at the front on a pair of domed bolts (Temple Bolts) either side of a securing latch. Felder and Hammer P/Ts also use this general mounting principle, where more information* is available. P/Ts with this system are designed so that the hinge alone sets the table alignment. The table, when lowered, should rest equally on both temple bolts before latching, and should not move when the latch is tightened. If the table does move, the setting will not hold, and the temple bolt heads will wear prematurely. Note that the latches should be adjusted so that when locked, they have their operating levers vertical.
The tables have to be set for both pitch (table not drooping at one end or the other) and roll (table width, level with axis of cutter block). It should not normally be necessary to adjust the pitch of the outfeed table, but if it has been removed from the machine, it should be set parallel with the machined surface of the cabinet under the cutterblock bearing, or the machined top of the bearing housing. If needed, see "Setting the Infeed Table" for method.
To set the tables, remove the power supply, the fence, the cutter guard assembly and the front cover joining the two tables. This allows complete access to the temple bolts and latches. All adjustment is referenced from the cutter block, so the outfeed table must be set to the cutter block.
Outfeed Table:
Assuming the hinge side is not to be adjusted, raise the outfeed table (beware! no lift catch!) and lower it gently onto the temple bolts. Does one touch before the other? Tighten the latch repeatedly; does the table move while tightening? A blue Rizla cigarette paper is a big help here (one thou thick). Place a paper over each temple bolt and lower the table; do not latch! Are both papers gripped? If not, adjust the lowest temple bolt. If so, latch and relatch three or four times, and then raise the table and inspect the papers. Is each paper equally marked? The graphite in the cast iron will make a spot on each paper, more efective here than engineer's blue. When correctly adjusted, the latch will quickly tighten, and a dial gauge** will show no table movement as a result of latching.
Now the height of the table above the cutter block is read by the dial gauge at the hinge side, by moving the gauge back and forth over the block itself (clear of the knives) to find the highest point. Then similarly check the latch side. Is the latch side, with latch tighened, higher or lower? Raise or lower the temple bolts by turning both through the the same angle. Check again by the cigarette paper method, that both temple bolts are equally loaded by the table, and recheck that the table is the same height above the cutter block at hinge and latch side.
Setting the Infeed Table:
Latch the outfeed table, and raise it clear of the knives with the outfeed lifting handle. Unlatch the infeed table, leaving it resting on the temple bolts. Place a straight edge on the outfeeed table at the hinge side, cantelevered over the infeed table. Raise the infeed table by its lifting handle, until it just contacts the bottom edge of the straight edge. Which end of the infeed table is lowest? At the cutter block? Or the infeed end? A feeler gauge may help.
The infeed table should be adjusted parallel to the straight edge by turning the grub screws in the hinge mounting (or base) (see USA manual). If the error is largest at the cutter block end, use the grubscrews nearest the block. If the error is greatest at the infeed end, use the grubscrews furthest from the block. Retighten the three bolts to secure the hinge base and recheck with the straight edge, with the table still unlatched. Continue to adjust until the table is even with the bottom of the straight edge. Keep the infeed table unlatched whilst adjsuting. (Felder point out that even their planer tables are not perfectly flat, having a "tolerance of several thousandths of an inch" so some judgement may be needed).
Move the straight edge to the latch side, and raise the infeed table untill it just touches the bottom of the straight edge. Lock and unlock the infeed table latch. Does the table move relative to the straight edge whilst latching? The temple bolts should be checked/adjusted as above, so that each bolt takes the same table load by the cigarette paper test. Then place the dial gauge at the hinge side of the infeed table; set the dial gauge to the highest point of the block. Then check the latch side.
Adjust the temple bolts by rotating each through the same angle, so that the width of the infeed table is parallel with the cutter block axis (table same height above block at both hinge and latch sides). Recheck the cigarette paper test. When correctly adjusted, the latch will quickly tighten, and a dial gauge** will show no table movement as a result of latching.
When correctly set, the top of the block, and the width of each table will be parallel. The straight edge can made to lie fully over both tables (by nudging the lifting handles) with little or no gap between tables and straightedge. These instructions may look indigestible, but the actual adjustment using the fag paper is in fact both quick and easy!
Assuming the knives have been corectly set, (not exceeding 1.1mm above the block, and level with the outfeed table at top centre), use the dial gauge to set the outfeed table 0.004" below the knives. Surface the edge of two boards about 3' long and place the cut edges together. Raise the outfeed table by 0.001" and repeat the check. Continue raising by 0.001" and re surfacing until the outfeed table is regarded as "set" when the two cut surfaces meet with the smallest of gaps at the centre i.e. very slightly concave. A convex result is not acceptable. If this cannot be achieved with the outfeed table between -0.001" and +0.004" below the knives, the table alignment needs further adjustment.
* Info on Felder P/Ts from Felder documentation via Felder Owners' Group.
**Dial gauge; best fitted at one end of a block of dense timber about 50x50x500. Screw 3 brass setscrews into base to make 3 'feet', levelling them on wet and dry on a flat surface. This will allways sit steady and reduce the effect of table tolerances and give repeatable readings. I made mine from a length of 25x50x3 RHS with a short length of 12x30 BMS bar bolted to one end, to hold the gauge out over the cutter block. The gauge stem fits in a hole-with-a-split and is tightened by a 6mm caphead bolt to close the split on the stem(like a pencil gauge).
The Jet family of P/Ts with dual-lift, or 'raise-together' tables has a UK manual lacking adjustment instructions. This is a problem, as the tables will require periodic checking and adjustment to allow for wear. The USA manual which can be downloaded from Jet's N. Amreican website, is a little better but still lacks some important details.
Dual Lift Table Mounting System:
Looked at from the operating position, each table is supported by a hinge at the back, and rests at the front on a pair of domed bolts (Temple Bolts) either side of a securing latch. Felder and Hammer P/Ts also use this general mounting principle, where more information* is available. P/Ts with this system are designed so that the hinge alone sets the table alignment. The table, when lowered, should rest equally on both temple bolts before latching, and should not move when the latch is tightened. If the table does move, the setting will not hold, and the temple bolt heads will wear prematurely. Note that the latches should be adjusted so that when locked, they have their operating levers vertical.
The tables have to be set for both pitch (table not drooping at one end or the other) and roll (table width, level with axis of cutter block). It should not normally be necessary to adjust the pitch of the outfeed table, but if it has been removed from the machine, it should be set parallel with the machined surface of the cabinet under the cutterblock bearing, or the machined top of the bearing housing. If needed, see "Setting the Infeed Table" for method.
To set the tables, remove the power supply, the fence, the cutter guard assembly and the front cover joining the two tables. This allows complete access to the temple bolts and latches. All adjustment is referenced from the cutter block, so the outfeed table must be set to the cutter block.
Outfeed Table:
Assuming the hinge side is not to be adjusted, raise the outfeed table (beware! no lift catch!) and lower it gently onto the temple bolts. Does one touch before the other? Tighten the latch repeatedly; does the table move while tightening? A blue Rizla cigarette paper is a big help here (one thou thick). Place a paper over each temple bolt and lower the table; do not latch! Are both papers gripped? If not, adjust the lowest temple bolt. If so, latch and relatch three or four times, and then raise the table and inspect the papers. Is each paper equally marked? The graphite in the cast iron will make a spot on each paper, more efective here than engineer's blue. When correctly adjusted, the latch will quickly tighten, and a dial gauge** will show no table movement as a result of latching.
Now the height of the table above the cutter block is read by the dial gauge at the hinge side, by moving the gauge back and forth over the block itself (clear of the knives) to find the highest point. Then similarly check the latch side. Is the latch side, with latch tighened, higher or lower? Raise or lower the temple bolts by turning both through the the same angle. Check again by the cigarette paper method, that both temple bolts are equally loaded by the table, and recheck that the table is the same height above the cutter block at hinge and latch side.
Setting the Infeed Table:
Latch the outfeed table, and raise it clear of the knives with the outfeed lifting handle. Unlatch the infeed table, leaving it resting on the temple bolts. Place a straight edge on the outfeeed table at the hinge side, cantelevered over the infeed table. Raise the infeed table by its lifting handle, until it just contacts the bottom edge of the straight edge. Which end of the infeed table is lowest? At the cutter block? Or the infeed end? A feeler gauge may help.
The infeed table should be adjusted parallel to the straight edge by turning the grub screws in the hinge mounting (or base) (see USA manual). If the error is largest at the cutter block end, use the grubscrews nearest the block. If the error is greatest at the infeed end, use the grubscrews furthest from the block. Retighten the three bolts to secure the hinge base and recheck with the straight edge, with the table still unlatched. Continue to adjust until the table is even with the bottom of the straight edge. Keep the infeed table unlatched whilst adjsuting. (Felder point out that even their planer tables are not perfectly flat, having a "tolerance of several thousandths of an inch" so some judgement may be needed).
Move the straight edge to the latch side, and raise the infeed table untill it just touches the bottom of the straight edge. Lock and unlock the infeed table latch. Does the table move relative to the straight edge whilst latching? The temple bolts should be checked/adjusted as above, so that each bolt takes the same table load by the cigarette paper test. Then place the dial gauge at the hinge side of the infeed table; set the dial gauge to the highest point of the block. Then check the latch side.
Adjust the temple bolts by rotating each through the same angle, so that the width of the infeed table is parallel with the cutter block axis (table same height above block at both hinge and latch sides). Recheck the cigarette paper test. When correctly adjusted, the latch will quickly tighten, and a dial gauge** will show no table movement as a result of latching.
When correctly set, the top of the block, and the width of each table will be parallel. The straight edge can made to lie fully over both tables (by nudging the lifting handles) with little or no gap between tables and straightedge. These instructions may look indigestible, but the actual adjustment using the fag paper is in fact both quick and easy!
Assuming the knives have been corectly set, (not exceeding 1.1mm above the block, and level with the outfeed table at top centre), use the dial gauge to set the outfeed table 0.004" below the knives. Surface the edge of two boards about 3' long and place the cut edges together. Raise the outfeed table by 0.001" and repeat the check. Continue raising by 0.001" and re surfacing until the outfeed table is regarded as "set" when the two cut surfaces meet with the smallest of gaps at the centre i.e. very slightly concave. A convex result is not acceptable. If this cannot be achieved with the outfeed table between -0.001" and +0.004" below the knives, the table alignment needs further adjustment.
* Info on Felder P/Ts from Felder documentation via Felder Owners' Group.
**Dial gauge; best fitted at one end of a block of dense timber about 50x50x500. Screw 3 brass setscrews into base to make 3 'feet', levelling them on wet and dry on a flat surface. This will allways sit steady and reduce the effect of table tolerances and give repeatable readings. I made mine from a length of 25x50x3 RHS with a short length of 12x30 BMS bar bolted to one end, to hold the gauge out over the cutter block. The gauge stem fits in a hole-with-a-split and is tightened by a 6mm caphead bolt to close the split on the stem(like a pencil gauge).
