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The pure rotational spectra of the alkali metal sodium and potassium monocarbides (NaC and $KC,X4\Sigma$) and methylidynes (NaCH and $KCH1$ and their deuterated isotopomers NaCD and KCD, $X~3\Sigma -$) in their ground vibronic states have been recorded using millimeter/sub-millimeter direct absorption techniques. This work represents the first spectroscopic information obtained for these molecules. The radicals were created using Broida-type oven/d.c. discharge methods by reaction of the alkali metal vapors and methane $(CH4)$ and deuterated methane $(CD4)$. The experiments covered the spectrum region 320-530 GHz, 9 transitions for NaCH, 5 for NaCD, 14 for KCH, 9 for KCD, 11 for KC and 8 for NaC were recorded, respectively. All six sets of data were successfully analyzed using either a $\mathrm{<mrow\; data-mjx-texclass="ORD">4</mrow>}\Sigma$ or a $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Sigma$ model, except NaC, for which due to overlap, only three data points out of four spin-components were available, therefor the fit is not as satisfactory as other. The spectra and the fitting results will be presented.