Machined Waveguide Components to Your Drawing
This page is for RF engineers and buyers preparing a drawing for machined waveguide sections, bends, twists, transitions or split-block channel assemblies.
It sets out which flange, passage and finish requirements the drawing has to carry, how each one can be checked, and what to send so quotations can be compared.
Closed Sections and Split Blocks Need Different Drawings
Machined waveguide components generally take one of two build forms.
A closed bend is reached only through its ports; a split block exposes the channel — concept illustration
An opened split block: channel, split-plane faces and pin holes can be inspected before closure.
A closed section, such as a straight length, bend, twist or transition, has a continuous passage that can only be reached through its ports once it is finished; depending on the design it is machined from solid or built from tube with flanges joined to it. A split block divides the passage between two halves, so channels, steps, irises and junctions are machined as open features and then closed with fasteners. The build form decides which internal dimensions can be measured directly and which interfaces the drawing has to control.
If your design could be made either way, state the form you have chosen or ask for both to be reviewed before quotation. The drawing set, inspection plan and price prepared for one form do not transfer directly to the other, and a change of form later usually reopens the RF design review.
Related: Waveguide and cavity machining · Defining waveguide drawing requirements
Closed sections
aperture at each port, length, bend radius or twist angle, the relationship between the two flanges, any flange-to-tube joint, and how the internal cross-section is verified.
Split blocks
channel layout in each half, split-plane faces, alignment pins, fastener pattern and the passage dimensions measured before closure.
Scope
this page covers the mechanical part made to your drawing. RF design, tuning and RF performance testing stay with your team unless a separate test arrangement is agreed for the order.
Flange Faces, Apertures and Alignment Pins
The flange is where your component meets the rest of the waveguide run, so its definition decides whether the part mates as intended.
The mating face, aperture, pin holes and any choke groove are defined together on the drawing.
Pin holes and aperture tied to the same datums so the joint does not form a step — concept illustration
Name the flange type and the standard or interface drawing it follows, then state which face is the mating face and the flatness and finish requirement that applies to it. For a choke flange, the choke groove geometry and its position relative to the aperture belong on the drawing. For a pressurised line, identify any gasket groove and the gasket it is designed for.
Alignment pins and their holes set where the aperture sits against the mating flange. Dimension the pin holes and the aperture from the same datums, and state whether pins are supplied, pressed in or left for your assembly. A flange face can be flat and still create a step at the joint if its pin holes are shifted relative to the aperture.
Related: Defining waveguide drawing requirements · Quality and inspection
Screw holes need detail too
state thread or clearance size, whether threaded holes are masked during plating and whether thread inserts are required. Each choice changes the finishing route and the quote.
Cross-Section, Internal Corners and Bend Geometry
The broad-wall and narrow-wall dimensions of the passage are the core of the RF design, and they need to hold along its whole length, not only at the ports.
Tool radius in milled corners and the cross-section held through a bend — concept illustration
In a milled channel, the corners between floor and side walls carry the radius of the cutting tool. State the maximum corner radius your design accepts, or say that square corners are required, so an alternative tool, split or process can be discussed before the part is quoted.
Bends and twists add a path to the cross-section. Define the bend type, centreline radius or mitre geometry, or the twist angle and length, and say how the cross-section is controlled through the transition. Where the internal geometry cannot be reached after manufacture, agree in advance whether it is verified by gauging at the ports, by measuring a sectioned first sample, which is an extra part quoted separately, or by controlling the route that produces it.
Related: 5-axis machining · Waveguide and cavity machining
Split Plane, Alignment Features and Fastener Pattern
In a split block, the two halves form the passage only when they close in the intended position. The split plane is a design decision. Many rectangular designs split along the centre of the broad wall, where the transverse wall current of the dominant mode is close to zero, while filter or junction layouts may need a different plane. Whichever you choose, the drawing should treat both halves and their joint as one defined interface.
Split-plane faces
flatness requirement on each half, and whether it applies before or after finishing.
Alignment
dowel pin holes or other locating features, and the fit you need between pin and hole.
Passage registration
channel position in each half dimensioned from the same alignment datums.
Fastener pattern
screw positions along the channel, thread type and any tightening sequence your assembly uses.
Pair identity
whether halves stay as marked pairs or must be interchangeable across the order.
Related: Waveguide and cavity machining
Keep the split under design control
a split-line or pin change proposed for machining reasons goes back to your RF design owner before the drawing is released.
Plating and Conductive Finish on Walls and Flanges
Internal walls carry the RF current, so their finish is part of the electrical design.
Internal walls, flange faces and masked holes marked as separate finish zones — concept illustration
A plated half with masked threaded holes; the drawing states which dimensions apply after plating.
Specify the finish system in full: base material and condition, any underlayer, the top layer, and the thickness requirement with the location where it is measured. Some designs exclude a nickel underlayer on RF surfaces; if yours does, write it on the drawing rather than leaving it to the finishing route.
State whether aperture and flange dimensions apply before or after plating, and mark surfaces that must stay masked, such as threaded holes, pin holes or a gasket groove. Plating thickness can differ between an open flange face and a deep internal corner, so a single thickness value without a location is hard to check and hard to compare between quotes.
Related: Materials and surface finishing · Surface finishing and dimensional requirements
- 01Machined state
dimensions and surface condition before finishing, recorded where your drawing asks for a pre-finish check.
- 02Masking
surfaces and holes excluded from the finish, marked on the drawing.
- 03Finish applied
finish system and thickness requirement at the stated measurement location.
- 04Final state
the dimensions and surfaces accepted after finishing.
Name the specification
where you use a plating or conversion-coating specification, give its designation and revision and any class or type option it contains.
Edges, Burrs and Cleanliness Inside the Passage
A general note such as 'break all sharp edges' can conflict with an RF design that needs crisp aperture, iris or step edges.
Port caps protect the flange faces and keep debris out of the passage after cleaning.
Mark which internal edges must be left sharp and burr-free, and which external edges may be chamfered. Burrs and chips inside a closed passage are hard to see and hard to remove, so state the cleanliness condition you need at delivery and how the ports are protected afterwards.
Related: Packaging and delivery · Packaging and identification requirements
apertures, irises, steps and channel edges at the split plane, left sharp and free of burrs.
chamfer or radius allowed where the drawing permits it.
no chips, loose particles or residue from machining or finishing at delivery.
caps or covers over flange faces for handling and shipment, so a dented flange or debris does not undo an accepted part.
How Each Waveguide Feature Can Be Checked
Agree the inspection plan feature by feature before the order is released. Some dimensions can be measured directly on an open half, while others are only accessible at the ports or after a first sample is sectioned. The method and stage for each characteristic are confirmed for your order; the table lists the questions to settle first.
| Feature | Checking options to discuss | What the record should state |
|---|---|---|
| Aperture at each port | Gauging or coordinate measurement at the flange | Port, characteristic number, revision and finish state |
| Channel width and depth in a split half | Measurement on the open half before closure | Half identity, locations measured and stage |
| Internal path of a closed bend or twist | Port gauging, a sectioned first sample or route control | Which method was agreed and what it covers |
| Flange face flatness | Measurement of the mating face with stated support | Face measured, area covered and condition |
| Pin holes relative to the aperture | Coordinate measurement from the drawing datums | Datums used and a result for each hole |
| Plating thickness | Measurement at the location named on the drawing | Location, method and finish specification |
A dimensional record is not an RF result
insertion loss, return loss or VSWR come from an RF test of a defined configuration, which is arranged separately.
From First Sample to Repeat Order
A waveguide prototype is usually machined, finished, assembled and then tested by the design team. Keep each sample identified through all four stages, so a test observation can be traced back to the halves, revision and finish state that produced it. If the design changes after testing, revise the drawing and list the affected features before the next sample is quoted.
For a repeat order, the reference is the accepted revision, finish specification, inspection plan and pair or interchangeability rule. State any change to these, including a different finishing source, so the repeat quotation is compared with the approved part rather than with an earlier assumption.
Related: Small-batch production · From an approved prototype to a controlled batch · What to clarify when a drawing revision changes
Step one: each sample carries the part number, drawing revision and pair identity.
Step two: matched halves keep one pair mark through finishing, assembly and testing.
Step three: accepted revision, finish and checks carried into the repeat order — concept illustration
Mark the pairs
if halves are matched at the prototype stage, ask for the pair mark on a non-functional surface and on every delivery document.
Records to Request With Each Delivery
Ask for records that match the characteristics you actually accept. Each record should name the part number, drawing revision and the serial or pair identity of the parts it covers. A generic report that does not reference the drawing features is difficult to use when a test result later has to be investigated.
Dimensional report
characteristics numbered against the drawing, with method and measurement stage.
Material document
grade and condition matching the drawing callout, traceable to the delivered parts.
Finish record
finish system, specification and thickness at the agreed location, where requested.
Pair and serial list
which halves or sections were supplied together.
Deviation record
any accepted departure from the drawing, with its approval reference.
Compare Waveguide Quotations on the Same Definition
Two quotes for the same drawing can describe different parts. Before comparing prices, check that each one assumes the same build form, finish system, inspection coverage and supplied items. A lower price that leaves out masking, pins or a pre-finish check is a different scope, not a cheaper version of the same part.
| Item to compare | Question to ask about each quote |
|---|---|
| Build form | Closed section or split block, and is any change to the split plane or corners proposed? |
| Flange hardware | Are pins installed, inserts fitted and screws supplied, or left for your assembly? |
| Finish | Full finish system, thickness location, masking and the before-or-after dimension rule? |
| Inspection | Which characteristics are measured, on how many parts and at which stage? |
| Sets and spares | Matched pairs, interchangeable halves or separate spare quantities? |
| Protection and documents | Port caps, packing and the records listed in the quote? |
Related Pages
Continue with the closest related part family or guide.
Microwave cavity housings
Cavity geometry, resonator posts, tuning holes, wall-to-cover contact and plating to define for machined filter and resonator housings.
Waveguide Drawing Requirements and Tolerances
Which waveguide features, datums, finish conditions and acceptance checks to define on the drawing before a machining quote.
Questions About Waveguide Component Orders
Can a standard flange be specified by name only?
A flange type name is a useful start, but the drawing should still show the mating face, aperture, pin holes and screw holes it relies on, or reference a specific interface drawing and revision. Flange families include variants with different pin arrangements and hole forms, so naming the exact variant avoids a part that fits one mating flange but not another.
How should a flange adapter between two interfaces be defined?
Treat it as two flange interfaces on one part. Reference both interface definitions, dimension both apertures and pin patterns from one datum scheme, and state the alignment needed between the two apertures. If the passage steps or tapers between the two cross-sections, define that internal geometry and how it is checked, because it cannot be seen once the part is finished.
Should split halves be ordered as matched pairs or interchangeable parts?
Matched pairs keep each set together as made and are simpler to control for prototypes. Interchangeable halves require alignment features and passage positions to be held so that any half fits any mating half, which changes the inspection plan. State which rule applies to your order and list spare halves as a separate quantity.
How should internal surface roughness be specified?
Give the requirement, the surfaces it applies to and the condition, before or after plating. Internal walls of a closed section are hard to reach with a stylus instrument, so agree before ordering whether the check is made on an open half, on a representative surface or by another method, and record which one was used.
Does a dimensional report confirm RF performance?
No. A dimensional report shows the measured characteristics of the delivered part. RF performance depends on the complete configuration, the test set-up and the acceptance limits. If you need an RF test, define the configuration and limits, agree separately who performs it, and link each result to the part serial and revision.
Discuss Your Waveguide Component
Send the drawing or a short description with the component type, waveguide size or flange standard, material and finish callout, and the quantity for your next build.
Sales contact (pending)
Name, role and photo to be confirmed
Drawings are optional for an initial discussion.
Start with the information you have; file exchange can be arranged afterward.
Name to be confirmed
Sales, company name to be confirmed
- Say whether the part is a closed section or a split block and which feature you want reviewed first.
- Drawings can follow after the first exchange.
Project Inquiry
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