British Letterpress

Tag: Maintenance

  • Setting Roller Height

    Setting Roller Height

    Since the gen­er­al pur­pose of a press is to ink a print­ing sur­face and impress paper against it, roller height has a big part to play in qual­i­ty print­ing. For the small­est print­ers there are the ​“small print­er” approach­es of set­ting large cap­i­tal let­ters in the chase; ink­ing those let­ters and then inspect­ing to see whether the face is inked, and whether ink has been trans­ferred to the beard of the type. The ide­al is to have ful­ly inked the sur­face with a min­i­mum of ink being applied to the beard of the type.

    The next stage is to use a roller set­ting gauge. These come in var­i­ous shapes and sizes. We’ll look here are the basic type that most small com­mer­cial print­ers would have. Flat gauges are typ­i­cal­ly a block of met­al machined to 0.918” high with a long han­dle: and have the advan­tage that they tend not to tilt and so skew the results. The aim here is to see a thin film of ink over the sur­face. No ink indi­cates rollers are too high; and ink that has been smeared or left on the sides indi­cates rollers are too low.

    Cylin­dri­cal gauges are more com­mon but can tilt when used. The aim here is to see a thin strip of around ⅛th of an inch of ink on the top of the cylin­der.

    A fur­ther step to pre­ci­sion was to use a spring-loaded set­ting gauge that includ­ed a dial or mark­er to show how low the rollers were on the machine. I am yet to see one in use!

    The Nether­lands Graph­ic Arts Research Insti­tute worked on estab­lish­ing real­is­tic tol­er­ances for let­ter­press mate­ri­als. They sug­gest­ed that type would still print per­fect­ly if it was with­in 0.0008” of 0.918”, and so any efforts to be more pre­cise than that would be a waste.

    F C Wal­ter, writ­ing in Print in Britain repeat­ed that he had heard a lec­tur­er stress­ing the need to be with­in an over­all lim­it of 0.0015”, and com­ment­ed that it would work ​“pre­ci­sion and the print­er to death”. He fore­saw that a “…print­er, who has top­pled, drunk with fas­ci­na­tion into pre­ci­sion-land where every­thing is beau­ti­ful but use­less.” He pro­posed an over­all lim­it of 0.0030”. The rea­son­ing was that 0.0015” could be so eas­i­ly dis­rupt­ed by stan­dard print­ing process­es (like plan­ing) that it could not be achieved. In con­text 0.0015” is around ¾ of the thick­ness of a cig­a­rette paper.

     

  • Maintaining Letterpress Machines

    Maintaining Letterpress Machines

    The key points in main­tain­ing all print­ing equip­ment are to keep it well-lubri­cat­ed and to keep your equip­ment clean.  As Jack Deller notes: the clean­li­ness of the over­all print­ing works and machin­ery is seen as a good indi­ca­tion of effi­cien­cy.

    Ensure that your press­es and oth­er machines are well-lubri­cat­ed reg­u­lar­ly and that the right points are greased.  Remem­ber that there may be some oil­ing points beyond eye lev­el or towards the bot­tom of the machine.

    Your press­es should be peri­od­i­cal­ly cleaned with an oily rag.  Where cor­ro­sion is found on the bed of the press it can be removed with fine car­bo­ni­um paper soaked in paraf­fin.

    In terms of mov­ing, ser­vic­ing and clean­ing machines thor­ough­ly here are some hints —

    • Cast iron is brit­tle: treat it as if it were glass and use either non-met­al ham­mers (like rub­ber, plas­tic or wood) or one of these mate­ri­als between the cast iron and the ham­mer
    • When remov­ing parts, replace nuts and bolts in their vacant holes.  Where this is not pos­si­ble, keep a small tin for these
    • For com­plex machin­ery con­sid­er using steel punch­es with let­ters to show which parts go where; or where gears should meet each oth­er.  Record the posi­tion of the machine when you begin to take it apart
    • Avoid cross­ing threads when undo­ing bolts, don’t use too much force
    • Remem­ber that tom­my pins and keys can be stuck on dirt, so clean first before try­ing to force them out

    In terms of equip­ment, a rec­om­men­da­tion is that ​‘an old suit­case’ or oth­er bag be found to con­tain the fol­low­ing items to help with low-lev­el print­ers’ engi­neer­ing

    • Deep tray to soak parts in paraf­fin to clean them
    • Pipe clean­ers to clear out oil­ing holes
    • Emery paper to remove dried ink
    • Paint brush to clean gears
    • Small tin to hold duct keys and oth­er small parts
    • Insu­lat­ing tape to shore up air tubes
    • Tweez­ers to remove oil­ing wicks
    • Torch
    • Brass, Rub­ber or Hide ham­mer
    • Screw­drivers
    • Span­ners
    • Oil­ing can
    • Tom­my bar
    • Rags
    • Cen­tre punch
    • Small chis­el
    • Oil and grease
    • Rags
  • Applying Precision Techniques

    Applying Precision Techniques

    “Pre­ci­sion begins in the com­pos­ing room” was the stan­dard cry from the mak­ers of com­pos­ing room equip­ment. They claimed that with­out this foun­da­tion oth­er work on pre­ci­sion would be wast­ed. A speak­er at a BPMF con­fer­ence – Mr. Philip J Wright of Bris­tol – expressed a slight­ly dif­fer­ent view and I’ll sum­marise it here.

    We do need to be pre­cise in the com­pos­ing room; but this will come to noth­ing if our let­ter­press machines are poor­ly-kept. It takes a lot of repeat­ed effort to get each forme accu­rate for print­ing; but less time to get a press real­ly accu­rate. Mr Wright sug­gest­ed start­ing with the press­es – and not the com­pos­ing room – to get imme­di­ate results. The test was to take an expert­ly pre­cise forme from anoth­er print­er and use your own machine: any ben­e­fits from this effort will be lost with a poor­ly main­tained machine, regard­less of the effort invest­ed in the forme.

    So, get your machine ship-shape first.

    Turn­ing then to the com­pos­ing room, we need to take a sys­tem­at­ic approach to pre­ci­sion – again to secure the great­est imme­di­ate ben­e­fit.

    • Height of Mate­ri­als
      While ​‘type high’ means 0.918”, dif­fer­ent ele­ments of a forme will have slight­ly dif­fer­ent heights: type in cas­es; type cast in-house; blocks; mount­ings etc. The first step here is to be able to accu­rate­ly mea­sure the heights of these things and work out the tol­er­ances that you can work with. This might need a com­bi­na­tion of dif­fer­ent approach­es to mak­eready
    • Hor­i­zon­tal Rela­tion­ships between Mate­ri­als
      This is about get­ting every­thing in the right place across the forme. Jack Deller not­ed that wood­en reglet in a 3” square might change shape by any­thing up to 6pts under pres­sure. Lin­ing up tables or draw­ing boards can be used to assure accu­rate posi­tion­ing; but more sim­ple approach­es can give ben­e­fits: using met­al or formi­ca fur­ni­ture in places of wood, for exam­ple.

    Over­all the approach needs to be defined by the type of work. For those using plates a great deal, bet­ter bases might be a quick and effec­tive improve­ment. For those doing mul­ti-colour work, lin­ing up would be crit­i­cal.

    The over­all scheme, though, must be get imme­di­ate improve­ments of one sort or anoth­er and use mul­ti­ple, small steps to get bet­ter results.