2 2REFURBISHING - Sewing Test/Preparation

[2] J - 1

The sewing test shouldestablish that:

The needle is set correctlyto pick up the lower thread.

The timing of the machine iscorrect.

The tensions are correct.

The machine sews at shortto long stitch lengths - andreverse if fitted.

The feed dog height andfoot pressures are setcorrectly.

The test is little different frommodel to model. Any variationsare covered as the test isexplained.

Each stitch is formed by the topthread being picked up by thehook and guided round thelower bobbin. This locks thetwo threads securely together.

The aim is to achieve stitchingwhere the tension is equal onboth top (needle) and bottom(bobbin) threads, so that theloops lie between the twopieces of material.

We do not know the variety offabrics, stitch lengths andthread sizes that will be usedwith the machine. So the bestwe can do is to adjust thetensions at a normal stitchlength with an average weightof fabric.

We can then test at other stitchlengths to show that themachine can be adjusted tocope with the changes.

Choose a piece of fabric for thetest. It should be of sufficientsize that you have room on it tosew lines of 3 to 4 inches (70 to100 mm) length.

This will allow you to work up areasonable speed and alsocheck the machines linecontrol. So a piece of 6 x 6 (150 x 150 mm) folded over isneeded.

The material should not beflimsy or stretchable. Curtainliner is our preference forweight and lack of pattern.

Always fit a new needle. It isessential that needles beperfectly straight and have asharp point.

Machines arrive with bent andblunted needles. Replace themand use them to clean difficultto get at places.

The test is best done with amedium size needle (14/90)and thread to suit.

This section does not containdetailed instructions on fittingneedles, threading up etc, asthese are covered in the usermanuals for each machine.

Keep one of each manual byyou for guidance. If this meansyou send us a machine withouta manual, note it on theRefurbishment Record on theoutside of the case.

Choose a different threadcolour for top and bottom. Itmakes it much easier to see thestitch formation.

Thread up the top and bottomaccording to the user manual.

PICKING UP THE LOWER THREAD

(1) With the presser foot leverraised, and the threadtake up lever at itshighest position, hold theend of the needle thread,leaving it slack from thehand to the needle.

(2)Turn the balance wheeltowards you until theneedle moves down andback up again to thehighest position. Pull upthe needle thread and thebobbin thread shouldcome as well.

Tip: If you leave the cover slideopen, you can watch the topthread encircle the lower bobbin.

INTRODUCTION

Lockstitch

PREPARATION

19.12.2007

1

2

2 2

Note: If the hook fails to pickup the top thread andcapture the lower thread, itcan be due to the followingreasons: You are holding the top

thread too tight.

The needle has not beenpushed up into the needleholder as far as it will go.

The needle is the wrongway round. (Flat side to theleft for 201, to the right forother models.)

The needle has beenthreaded the wrong way.(From right to left for the201, left to right for othermodels).

The needle is bent. Alwaysstart with a new needle.

The machine timing needsadjustment. This is rare, soit is covered in the section

Advanced Techniques.

Guide the top thread throughthe slot in the presser foot andlay both threads towards theback of the machine.

The following paragraphsassume that you have set thelower tension correctly.See page [2] H-3 for further help.

(3) Insert the folded testpiece and lower thepresser foot. Choose a

medium stitch length tostart the test.

(4) Sew a seam down most ofthe length of the cloth,stop and turn the fabricthrough 90 so you canexamine the results.

Note: Do not try to help thefeeding of the work by pullingthe material, as this may deflectthe needle and cause it tobreak. The cloth should feedwithout assistance if the footpressure and feed dog heightare set correctly.

TensionTip: With contrasting colouredthread on top and bottom, it iseasier to see which thread islooser.

(5) The diagram shows theloops of the bottomthread visible on top ofthe fabric.In this case, loosen thetop tension a little and tryagain. (Turn the thumb-nut anti-clockwise.)

(6) If the top thread loops arevisible below the workpiece as in this diagram,tighten the tension a littleand try again. (Turn thethumbnut clockwise.)

If you are lucky - or havepersevered - the tension willbe just right.

Note: It is not always easy toobtain as perfect a result as inthe diagram. With thinnermaterials, particularly, you willhave to settle for nearperfection.

As you test at various stitchlengths, you will probably haveto lessen the top tension at thelongest stitch. This is normal.

If you can adjust the tensionbetween too loose and too tight,then the subsequent user willhave the same control whenchanging fabrics, weight ofthread etc.

Stubborn top loops underthe fabric

If you still have an apparentlyloose top thread even at thepoint that the thread snaps orthe material buckles, there arethree possible causes.

The cotton is not threadedthrough the tension checkspring - or the spring isineffective.

66/99 only, the top thread isnot passing between thelower bobbin and theretainer arm easily. (If youleave the cover plate openyou can watch this at slowspeed.) See page [2] H-2(9).

The feed dog is set too high.In this condition, the feed

REFURBISHING - Sewing Test

[2] J - 2

SEWING TEST

19.12.2007

3

4

5

6

2 2

dog rises up too far on itsreturn journey, and feedsthe material backwards,shortening the stitch afterthe top thread has beenpulled through the tensionplates, so that too muchthread remains.

Missing StitchesThe stitches should all be of thesame length. If some pickupsof the lower thread have beenmissed, the cause will be oneof the reasons given on theprevious page for not pickingup the lower thread. The solu-tions are the same.

PuckeringThe material has to be pulledthrough the machine by thefeed dog. The presser footholds the material firmlyagainst the feed dog. Makesure the presser foot screw isscrewed down enough to pro-vide this pressure. (Enoughpressure is also needed tokeep the seam straight.)

If this fails to solve the problem,it is because both tensions areset too high, the feed dog can-not pull the fabric throughagainst the resistance of thetensions - so the fabric slips.

Check the lower bobbinthread tension and startagain.

Stitch length controlWhen you have achieved a sat-isfactory stitch formation at amedium setting, try stitching atvarious settings of the stitchlength control.

At the maximum setting you willprobably have to reduce thetop tension to achieve a bal-anced stitch.

Reverse StitchingReverse stitching is availableon 201s and some late model

99 machines. This functionshould be tested. It is normallyused only for finishing seams,so do not alter the tension - justcheck that it works.

Completion of TestWhen you are satisfied that themachine is sewing properly at arange of stitch lengths the sew-ing test is complete.

And finally. . .

(7) Leave the piece of test fab-ric under the presser foot. Thisdemonstrates that the machinehas been tested and is workingperfectly.

(8) Remove the cotton reelfrom the spool pin, un-wind a few inches of cot-ton then cut it off andwind the end a few timesround the pin.

Leaving the machine threadedin this way will hopefully helpthe recipient to follow thethreading sequence. (Cottonreels inevitably fall off in transit.)

(9) Add the spare needles,bobbins and handbook ifyou have them, give themachine a wipe with aclean cloth and completethe paper work.

(10)Tie up the handle to thebalance wheel and thehandle bracket to avoid itbeing damaged in transit.

REFURBISHING - Sewing Test/Completion

[2] J - 3

19.12.2007

10

7

8

9