CMTA
Practical guides, written by the people who make the parts
Application guides, checklists and explainers for engineers and buyers — published with a named technical reviewer and a last-updated date as each one is completed.
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- Written for engineers
Published guides
Written by the people who make the parts
Practical engineering guidance, not sales copy. Each guide answers one question an engineer or buyer actually asks before sending a drawing — including, where it applies, the answer that says do not buy anything.
Tool holders
4 guidesWhen a custom tool holder is justifiedA custom holder is worth it when the geometry of your operation — reach, clearance, interface or combined operations — makes every catalogue holder a compromise. It is rarely worth it purely to save money on a standard size. The test is whether the constraint is geometric or commercial.Read the guide6 minWhat actually causes holder runoutRunout is not a property of the holder. It is the sum of the spindle, the interface, the holder body, the clamping element and the tool, and each contributes independently. Replacing the holder when the spindle taper is the dominant term is the most common and most expensive mistake in this area.Read the guide7 minWhat decides a VTL holder's designVTL holders fail in predictable ways: insufficient rigidity for the depth of cut, the wrong slot fit, or a body that cannot present the tool at the required reach without deflecting. Getting the turret slot, cutting direction, reach and expected load right at enquiry stage avoids nearly all of it.Read the guide6 minLocalising imported toolingThe case for localising imported tooling is rarely just unit price. It is landed cost plus the working capital tied up in a long lead time, plus the risk carried by a supply line you cannot expedite. Those are the terms the comparison should be made in — and sometimes they still favour the import.Read the guide8 min
Precision components
4 guidesWhat a good RFQ drawing includesA quotable drawing states the revision, the material and condition, the dimensions that control function with their tolerances, the surface finish, any heat treatment or coating, the quantity now and expected, and the date you need it. Anything missing becomes an assumption, and assumptions are priced defensively.Read the guide7 minShaft, bush and sleeve tolerance basicsA fit is a relationship between two parts, not a property of one. Specifying a shaft tightly without stating what it goes into produces parts that are individually correct and collectively unusable. Decide the fit first, then distribute the tolerance between the two components.Read the guide7 minChoosing between machining and grinding routesTurning removes material quickly and is usually enough. Grinding is the answer when the part is too hard to cut, when form and finish requirements exceed what turning holds reliably, or when the feature must be corrected after heat treatment. The decision is usually made by hardness and by what happens between operations.Read the guide7 minPrototype to repeat productionA prototype proves a part can be made. Repeat production proves it can be made the same way again. What bridges the two is not the part itself but the record: the approved drawing revision, the process route, the fixturing and the inspection results that showed it was right.Read the guide6 min
Fixtures
4 guidesJig versus fixture, and why the distinction mattersA jig guides the cutting tool as well as holding the work. A fixture holds and locates the work but does not guide the tool — the machine does that. On modern CNC equipment most of what people call jigs are fixtures, and treating one as the other leads to designs that cost more than they need to.Read the guide6 minDatum and clamping considerationsA part machined from the wrong datum can measure within every tolerance on the drawing and still fail to assemble. The fixture's datum scheme should follow the part's functional datums, and the clamps should push the part onto those locators rather than away from them.Read the guide7 minFixture-driven cycle-time reductionWhen cycle time needs to come down, the instinct is to cut faster. Workholding often has more to give, because loading, unloading, indexing and second operations are time the spindle spends not cutting — and unlike feeds and speeds, reducing them costs nothing in tool life.Read the guide6 minInspection fixture planningAn inspection fixture exists to answer one question quickly and repeatably: is this part acceptable? It should locate from the part's functional datums — the surfaces that matter in the assembly — which are not always the ones the machining fixture used.Read the guide6 min
Reverse engineering
5 guidesWhat can be recreated from a sampleGeometry recovers well from a sample, even a worn one, because worn surfaces can usually be reconstructed from the surfaces that did not wear. Material and heat treatment do not recover from measurement alone — they have to be tested or inferred from function, and the difference should be stated openly rather than assumed.Read the guide7 minRisks when the material is unknownA replacement part can match the original in every dimension and still fail within weeks if the material or its treatment is wrong. Unknown material is the single largest risk in reverse engineering, and the responsible handling is to test, to reason from duty, and to record the decision — never to quietly assume.Read the guide7 minThe obsolete-parts workflowWhen a part fails and the OEM no longer supplies it, the sequence that works is: stabilise the situation, secure the evidence, establish feasibility, approve a drawing, make and verify one, then decide whether to hold a spare. The most common mistake is skipping straight to manufacture and discovering the sample was the only reference.Read the guide7 minSample to approved drawingThe drawing is where reverse engineering becomes something you own and can reorder against. It should distinguish what was measured directly from what was reconstructed, state the material decision and its basis, and be reviewed by someone who knows the application before it is approved.Read the guide6 minKeeping an older machine productiveA machine losing OEM support has not become unusable — it has become your responsibility. The question is whether its mechanical condition justifies keeping it, and if so, which handful of parts represent the real risk. Usually it is a short list, and it can be dealt with before anything fails.Read the guide7 min
Productivity
5 guidesHow to measure setup time honestlySetup time is the interval between the last good part of one job and the first good part of the next. Measuring from 'machine stops' to 'machine starts' flatters the number and hides the part that usually costs the most: everything that happens before the operator reaches the machine.Read the guide6 minTooling symptoms that reduce throughputTooling problems rarely announce themselves as tooling problems. They appear as chatter someone has learned to live with, tool life that varies for no clear reason, a cycle time that has crept up, or scrap nobody has traced. Each symptom points at a different cause, and reading them correctly avoids replacing the wrong thing.Read the guide7 minEstablishing a cycle-time baselineAn improvement is only as credible as the baseline it is measured against. A defensible baseline breaks the cycle into its elements, is measured across more than one run, and records the conditions — part, machine, operator, material — so a later comparison is like for like.Read the guide6 minRecovering from a production delayWhen a line is stopped for a part, the first hour matters more than the next day. Establish exactly what is needed and what would be acceptable as an interim, describe it in a form somebody can act on immediately, and be explicit about which requirements are genuine and which are preference.Read the guide6 minWhen redesigning a part beats remaking itA part that fails once is an incident. A part that fails repeatedly is a design or a duty problem, and remaking it identically guarantees the next failure. The decision is whether to change the part, change what surrounds it, or accept the replacement cycle as the cheapest option — which it sometimes genuinely is.Read the guide6 min
Special purpose machines
4 guidesWhen a special purpose machine makes business senseA special purpose machine is justified when one operation repeats at high enough volume, for long enough, that a dedicated machine costs less over its life than doing the work on general-purpose equipment. The decision turns on the stability of the requirement as much as on the volume.Read the guide7 minDefining SPM acceptance criteriaAcceptance criteria decide when a machine is finished. Agreed before the build, they are a specification both sides design toward. Agreed afterwards, they become an argument conducted under pressure, usually while production waits.Read the guide7 minSemi-automatic versus automaticAutomating the operation and automating the handling are different projects with different economics. The operation is usually the easier and cheaper half. Handling — feeding, orienting, presenting and removing parts — is where cost, complexity and downtime concentrate, and where a full automation case most often fails to pay back.Read the guide6 minPreparing an SPM requirement briefA good brief describes the problem and the constraints, not the machine. Specifying a solution in the brief narrows the proposals to variations on your idea; describing the requirement lets builders propose approaches you had not considered — and makes the resulting quotes comparable.Read the guide7 min
Sourcing and supply
3 guidesQualifying a precision machining vendorMost vendor qualification checks paperwork. The questions that actually predict whether a supplier will perform are about boundaries: what they do in-house versus coordinate, what they measure and how, what they do when something goes wrong, and whether they will tell you when a job is not for them.Read the guide8 minSecond-sourcing a critical componentA second source is insurance, and like any insurance it is worth buying only for risks that would actually hurt. The components that justify it are the ones that would stop production, have a long replacement lead time, and currently come from one place — usually a short list, and usually known to the people who maintain the machines.Read the guide7 minWho owns the part across processesWhen a component passes through machining, heat treatment, grinding and coating at four separate suppliers, each is responsible for its own step and nobody is responsible for the finished part. The failures happen in the gaps — allowances, handling, sequence — and they are the hardest to resolve because everyone's own work was correct.Read the guide7 min
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FAQ
Frequently asked questions
The questions engineers and buyers ask before sending a drawing. If yours is not here, ask it directly — you will get an engineer's answer, not a brochure.
Still have a question?
Talk to Anita M.N, Managing Partner, or send the drawing and let the review answer it.
How do I choose the right tool holder?
Start from the machine interface, the tool and the operation; then reach and clearance; then rigidity and runout. Each product page lists the inputs for that family.
What should an RFQ drawing include?
Revision, material, critical tolerances and fits, surface finish, heat treatment or coating, quantity and any inspection requirement.
When is reverse engineering appropriate?
When no drawing exists or can be obtained, the sample allows functional surfaces to be measured or reconstructed, and the part is mechanical.
How can setup time be reduced?
Measure where the time actually goes, then remove steps with pre-set holders, quick-locating fixtures and combined tools — trialled and measured.
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