Tension Adjustment & CalibrationThis article kindly submitted by Charles DayThe calibration of tension on Singer sewing machines is quiet straight forward, but it does have to be performed in the correct order. The bottom tension MUST be correctly set BEFORE the top tension is adjusted.BOTTOM TENSIONUnder normal circumstances the bottom tension does not change in use, so once set correctly it should not have to be checked again. The need to adjust the bottom tension therefore mainly applies only to second hand machines you are not used to, or if the bobbin holder is changed for some reason.The adjustment principle of the bottom tension is similar for all Singer machines whether they use the vibrating shuttle boat type bobbin case (VS, 28, 128 etc.), the horizontally mounted removable bobbin case (15, 221, 222, 301) or the oscillating shuttle carrier with drop in bobbins (66, 99, 201 etc). In all cases the tension is provided by a small bent metal spring which traps the thread between the body of the bobbin case/carrier and the spring. The spring is slightly arched with a small adjusting screw that controls the pressure of the spring on the body and thus how much pull is required for the thread to slip between the two.

Lower Tension Adjusting ScrewIf you have a spring balance, it is simply a matter of removing the bobbin holder, inserting and threading up a bobbin and then pulling on the end of the thread in the normal direction with the spring balance. The target figure should be around 30 to 40g. (1-1/4 to 1-1/2 oz) but it does not have to be too precise. However most people dont have a spring balance handy, so alternatively you can tie a weight of the correct amount onto the thread and then jerk the bobbin gently upwards. This should cause 2 to 5 cm (1" to 2") of thread to slide through, but not for it to unwind freely.If you don't have a set of small weights, then you can use digital scales to weigh sugar, sand etc into a small ziplock bag to use instead.If the tension needs to be adjusted then it is simply a matter of tightening the screw near the centre of the spring to increase the tension, or loosening it to decrease the tension. Normally only slight movements are needed and so 1/16 to 1/8 of a turn should be ample steps before retesting.

TOP TENSIONOnce the bottom tension is set correctly, the top tension should provide a sufficient adjustment band to cater for the full range of materials and threads that may be used. If the lower tension is incorrectly set, then the machine may still sew but the upper tension may have to be at an extreme setting to compensate and this can cause tight or loose stitching, or thread breakage under some conditions.Early Singer models had a simple arrangement of a knurled nut pressing a spring against 2 tension discs through which the upper thread passes. Tension adjustment is then a simple trial and error process of adjusting this nut so that a perfect lockstitch is formed. A fraction of a turn on the knurled nut in either direction is all that is usually required to suit different conditions.Later models used an upgraded upper tension control that incorporated a numbered dial into the adjustment nut. These should be calibrated so that the machine produces a perfect lockstitch on 2 layers of medium weight cotton fabric with the dial set between 4 and 5. If this is not the case then it needs to be re-calibrated so that it does.Fortunately this is a simple process that doesnt require any dismantling of the assembly.The first thing to do is run a test stitch using 2 medium thicknesses of fabric to determine the correct position of the upper tension knob so that the machine makes a correct stitch having the right balance of top and bottom tension.Then without turning the knob, use a thumb to push back firmly on the numbered ring on the tension assembly so that it moves against its spring away from the knob at the front and into its shroud.

Upper Tension CalibrationIf you look carefully in the gap between the two parts you will see there is a series of 16 holes drilled around the front of the dial plate. You should also see that at one point in the rear flange of the knob there is a small shiny metal pin which projects out the back of the flange. When the dial plate is released this pin engages into one of the holes and allows the dial plate and knob to rotate as one. When releasing the dial plate it is necessary to check that the pin does correctly enter one of the holes, and if not to move it slightly until it does.By turning the dial plate whilst it is pressed back, and then releasing it again, it is possible to alter the relationship between the knob which controls the tension and the dial which displays it. We are looking for a situation where one full turn of the knob and dial provides a range of tensions from maximum to minimum and so the basic default condition should be between 4 and 5. You therefore need to rotate the dial plate to this setting before releasing it.Finally, retest the machine. If necessary repeat the adjustment process until it is right. It is not necessary to get it spot on because the default setting of 4-5 is only a starting point from which to work. However, in practice it is unlikely to ever need anywhere near the extremes of the upper tension range that the knob provides between its limits of 0 and 9.

Singer Oscillating Shuttle Machines RetimingEnsuring that the needle/shuttle timing is correct for oscillating shuttle machines (VS, 27/28K, 127/128K models) is a 4 step process. The first step is to ensure that the needle bar is set to the correct height. After this the height of the shuttle carrier must be checked and the shuttle clearances set. Only when these are all correct can the timing of the shuttle can be checked and if necessary adjusted.Setting the Needlebar HeightTurn the balance wheel towards you until the needle bar reaches its lowest point. In this position the gap between the bottom of the needle stop screw 'C' in the needle bar and the top of the throat plate 'E', should be 13/16. TIP use the shank of a 13/16 drill as a gauge.

Needlebar HeightIf the height of the needle bar needs to be reset, then loosen both screws 'D' in the needle bar clamp and adjust its position accordingly, before tightening them again and then re-checking the gap. The range of adjustment is approx. 1/32. If this range is not sufficient to ensure the correct setting, then the needle bar cam and pin should be checked for wear, and if necessary replaced.Shuttle Carrier HeightInsert a needle fully into the needle clamp and then rotate the balance wheel until the point of the shuttle reaches the centreline of the needle. The point of the shuttle should then be 1/16 above the top of the needle eye. Slight corrections can be made by bending the shuttle carrier arm close to where it is mounted onto the bell crank. Care must be taken not to over bend the carrier arm or it may foul the slide plate, or it can prevent the correct formation of stitches.

Shuttle Carrier HeightShuttle Thread ClearancesThe shuttle clearances need to be checked in 4 positions using a narrow 0.018 (0.45 mm) feeler gauge. The points to be checked are the gap between the shuttle and the raceway where the shuttle starts to curve in towards the point, the gap between the heel of the shuttle and the raceway, the gap between the end of the shuttle and the carrier and the gap between the shuttle body and the carrier spring.

Shuttle ClearancesThe clearance between the shuttle and the raceway can be adjusted by loosening the screw that connects the carrier to the belt crank. The clearance between the end of the shuttle and the carrier spring can be adjusted by slightly bending the carrier spring.Shuttle TimingIt is important that the above checks are all made before checking shuttle timing. The procedure for timing the shuttle varies depending upon whether the machine has a timing mark in the shuttle raceway.For machines without a timing mark: Turn the balance wheel towards you until the needle reaches its lowest point and then rises 3/32. That is when the gap between the bottom of the needle stop screw and the throat plate is 29/32. At this point the point of the shuttle should align with the centreline of the needle.

Shuttle TimingFor machines with a timing mark: With the machine supported upside down, turn the balance wheel towards you until the needle reaches its lowest point. At this position the tip of the shuttle point should align with the timing mark 'M' in the shuttle raceway.

Timing MarkAdjusting the shuttle timing:The timing of the shuttle is adjusted by the eccentric pin in the pitman link. The procedure is slightly different depending upon the model. For 27K/127K machines - after loosening the lock nut 'S' the eccentric pin 'T' should be turned until the high point of the eccentric is facing towards you (the back of the machine) and then rotated to the right (clockwise) until the point of the shuttle reaches the timing mark 'M'. For 28K/128K machines - the procedure is similar except that the starting position is with the high point of the eccentric away from you (to the front of the machine).

Timing AdjustmentSinger 400 Series Top Gear ReplacementNEW - Vertical Top Gear #155819

Top Gear #155819Stock Code : D1294New vertical top gear for many 400 series machines.Fits models - 413, 416, 418, 447, 449, 457, 466, 477 & 478price: 9.60

The main content for this article kindly submitted by Charles DayMany of the Singer 400 series of domestic sewing machine (including models 413, 416, 418, 427, 457, 466, 477 and 478) were only intended for light domestic use. Over-working these machines on heavy materials, such as denim or leather, is quite liable to break the plastic vertical gear in the top of the machine. This gear transfers the drive to the bobbin mechanism. This type of breakage becomes even more likely as the plastic fatigues with age. Fortunately, replacement of the gear is very easy. Provided the correct procedure is followed, it should take no longer than 15-30 minutes.

Broken GearSTEP 1 PREPARATION:Remove the needle, needle plate and bobbin from the machine. It can be easier later on if the bobbin case is also removed, but this is not essential. It is released by lifting the black coloured bracket about " (6mm) and then sliding it to the right. Next take off the needlebar cover at the left of the machine and the plastic cover on the top arm by undoing its 2 screws so that the top mechanism is exposed.The next task is to remove the plastic plate which covers the controls area. To do this unscrew the bobbin winder stop at the top right and then undo the 2 small screws at the bottom of the plate and the 1 at the top. Finally remove the screw on the left side, but note that this screw has a spring retainer inside the top of the machine. It will probably be necessary to stop it turning to remove the screw, but in any case care should be taken not to lose it inside the machine. Set the stitch length lever to zero to make removing the plate easier.

Top Cover & Controls Plate RemovedTo the left of the newly exposed area there is an aperture through which the retaining setscrew for the vertical gear can be accessed. There is a small removable panel at the bottom of the aperture held in by 2 screws. It is much easier if this panel is removed, although it is not essential to do so.

Access ApertureCarefully place the machine on its back and remove the base panel which is held by a single nut. Remove the toothed belt tensioning cam (single central screw) and take off the timing belt.STEP 2 REPLACING THE GEAR:Rotate the vertical gear so that its retaining setscrew is in line with the access aperture. If the gear teeth are broken then turning the balance wheel may not also turn the vertical gear as it is should. In that case turn the toothed belt pulley at the other end of the gear shaft underneath the machine. Once the gear setscrew is in line with the access aperture insert a flat bladed screwdriver and loosen the setscrew. If this is done with the machine upright the gear shaft may drop through. Be careful to avoid the shaft falling out completely, or carry out this step with the machine laid on its back. Once the setscrew is loose, pull the gear shaft downwards by about 1" (25mm) until it is free of the gear. Remove the old gear and replace it with a new one.

Removing GearPush the gear shaft upwards again so that it enters the bore of the gear, making sure that the flat at the top is aligned approximately with the setscrew in the gear. Tighten the setscrew whilst applying gentle pressure to the bottom of the shaft to ensure there is no vertical free play in the shaft.STEP 3 INITIAL REASSEMBLY:Reassembly needs to be carried out in 2 stages so that the hook can be re-timed in between them. Replace the small filler panel at the bottom of the access aperture and then refit the plate to the controls area. This is just a reversal of the dismantling procedure.Underneath the machine, refit the toothed timing belt and the tensioner device so that the belt rides over it. The tensioner should be rotated to give a suitable belt tension which is not loose, but not too tight either. The long length of the belt should deflect about " (12mm) if pressed in the middle.

Timing Belt & TensionerSTEP 4 RETIMING:Whenever the timing belt has been removed it is necessary to retime the machine so that the hook is in the correct relationship to the needle.Before starting, make sure that on zigzag machines the needle is set to the central straight stitching position. Double check this by inserting a needle and temporarily replacing the stitch plate and lowering the needle to it. (Do NOT pass the needle through it yet). If the needle is central to the hole in the stitch plate then remove the plate again and continue.Underneath the machine loosen the 2 setscrews holding the pulley onto the bottom of the bobbin mechanism shaft so that it rotates freely. Working with the machine on its back, hold the pulley still whilst turning the oscillating hook with theother hand so that its hook is pointing to the back of the machine.Now gently turn the balance wheel towards you until the needle reaches its lowest position. You will see the lower timing mark near the top of the exposed part of the needlebar.

Lower Timing MarkContinue rotating the balance wheel a few degrees until the lower timing mark rises to be exactly flush with the bushing. At this point the point of oscillating hook needs to be exactly aligned with the needle before tightening both of the pulley setscrews under the machine. After tightening the pulley setscrews check that nothing has moved by turning the balance wheel once until the timing mark is again flush with the bushing and check that the hook is just opposite the needle.

Align Hook With NeedleSTEP 5 FINAL REASSEMBLY:All that is left now is to put the machine back together. Refit the bottom cover onto the machine, the needle plate, the needlebar cover and finally the plastic cover onto the top arm. Thread up and sew test the machine.

Singer 400 Series RetimingThe main content for this article kindly submitted by Charles DayMany of the Singer 400 series of domestic sewing machine (including models 413, 416, 418, 427, 457, 466, 477 and 478) were only intended for light domestic use. Whenever any part of the drive train to the needlebar or bobbin has been moved, or replaced, it is necessary to retime the hook so it is in the correct relationship to the needle.The needle bar has 2 timing marks which are used to set the needlebar position and its relationship to the bobbin hook mechanism.

Timing Marks with Needlebar RaisedSetting the Needlebar HeightWhen the needle bar is in the fully downward position the upper timing mark should be exactly flush with the bottom of needlebar bushing. If it not, then loosen the setscrew on the needlebar lever and adjust accordingly.Timing The HookTo prepare the machine, remove the cover from the underside of the base, the needlebar cover plate, the stitch plate and the bobbin. It can be easier later on if the bobbin case is also removed, but this is not essential. It is released by lifting the black coloured bracket about " (6mm) and then sliding it to the right.Before starting the timing process, make sure that on zigzag machines the needle is set to the central straight stitching position. Double check this by inserting a needle and temporarily replacing the stitch plate and lowering the needle to it. (Do NOT pass the needle through it yet). If the needle is central to the hole in the stitch plate then remove the plate again and continue.Underneath the machine loosen the 2 setscrews holding the pulley onto the bottom of the bobbin mechanism shaft so that it rotates freely. Working with the machine on its back, hold the pulley still whilst turning the oscillating hook with the other hand so that its hook is pointing to the back of the machine.Now gently turn the balance wheel towards you until the needle reaches its lowest position. You will see the lower timing mark near the top of the exposed part of the needlebar.

Timing MarkContinue rotating the balance wheel a few degrees until the lower timing mark rises to be exactly flush with the bushing. At this point the point of oscillating hook needs to be exactly aligned with the needle before tightening both of the pulley setscrews under the machine. After tightening the pulley setscrews check that nothing has moved by turning the balance wheel once until the timing mark is again flush with the bushing and check that the hook is just opposite the needle.

Align Hook With NeedleAll that is left now is to put the machine back together. Refit the bottom cover onto the machine, the needle plate, the needlebar cover and finally the plastic cover onto the top arm. Thread up and sew test the machine.